Perch seed multi-dimensional low-stress efficient domestication method

Abstract

The present application belongs to the technical field of aquaculture, and aims at the problems of lack of smooth gradient in bait transition, disconnection between acoustic domestication and bait domestication, lack of behavior quantitative index, and lack of systematic domestication technology for Peridermum ilishae, and provides a multi-dimensional low-stress efficient domestication method for Peridermum ilishae fry, before each feeding, the acoustic conditioned reflex is established for Peridermum ilishae by knocking sound, and a double foraging synergistic mechanism of 'auditory nerve activation + bait gradient adaptation' is formed; artemia and commercial feed are used as feed, and the Peridermum ilishae is fed according to the daily decreasing gradient method of artemia amount, so that the feeding behavior is stable and coherent during the whole transition period; the water quality is managed and controlled according to the ammonia nitrogen concentration and nitrite in the recirculating aquaculture system, so that the water quality is stable and controllable, and the water quality collapse is effectively prevented. The behavior domestication effect of the method on Peridermum ilishae fry is remarkable, the domestication period can be shortened, the operation can be carried out according to the standardization, and the technology has strong replicability.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, and in particular to a multi-dimensional, low-stress, and efficient domestication method for Ili perch fry. Background Technology

[0002] Ili perch ( Perca schrenkii The Ili perch (Perciformes spp.) is a unique carnivorous fish species found in the Balkhash-Ili River and Emin River-Ala Lake systems, belonging to the genus Perciformes in the family Perciformes. Juveniles feed on planktonic crustaceans (cladocerans and copepods), while adults become predatory, preying on small fish and aquatic insects. Historically, it was an important regional economic fish, with an average annual yield of 564.3 tons in Lake Balkhash during the 1950s and 60s. However, due to invasive species, ecological degradation, and overfishing, the population has declined sharply. Currently, in Xinjiang, my country, it exhibits characteristics of smaller individuals and extremely low catches. Therefore, the artificial domestication and aquaculture of the Ili perch is of significant value for resource conservation and industrial development.

[0003] Currently, the existing technologies that are closest to the domestication of Ili perch fry mainly fall into the following two categories: (1) Method for acclimatizing pikeperch to artificial feed: This method was proposed by the Xinjiang Uygur Autonomous Region Fisheries Research Institute and patented in 2014 (application number 201410149678.6). It adopts a four-stage gradual transition method: "live bait → fish paste → soft pellet feed → hard pellet feed". Specifically: from day 3 to 7, live bait is fed and the pond wall is gently tapped to provide ecological reinforcement; from day 8 to 14, the amount of live bait is gradually reduced and the amount of fish paste is increased by 15% of the total weight each day; from day 15 to 30, artificial feed is used for acclimatization, and finally, the pikeperch are switched to hard pellet feed. The survival rate of acclimatization using this method can reach 73.4%. However, this acclimatization method has the following drawbacks: ① The acclimatization cycle is too long: it takes more than 30 days in total, which results in high time and breeding costs; ② The feed transition is complex: it requires going through four stages: live feed → fish paste → soft pellets → hard pellets, which is cumbersome to operate, and the fish paste is prone to decay and pollutes the water quality; ③ Water quality control lacks a quantitative model: no water quality prediction method based on feed amount is provided, and the problem of ammonia nitrogen accumulation is prominent in the early stage of acclimatization; ⑤ The acoustic acclimatization is incomplete: it only involves "lightly tapping the pond wall" on the 3rd to 7th day, and a complete signal-reward coupling mechanism has not been formed.

[0004] (2) Rapid feeding conversion method for largemouth bass / California bass: This method was proposed by the Suqian Agricultural Research Institute of Jiangsu Academy of Agricultural Sciences and was patented and authorized in 2018 (application number 201810791084.3). This method involves withholding food for 24 hours when the seedlings reach a length of 2 cm, and then rapidly completing the training in 2-3 days at a ratio of 20%, 50%, 80%, and 100%, with a seedling survival rate of over 60%. However, this method has the following disadvantages: ① Rapid feeding conversion leads to high stress: The transition from live bait to commercial feed is completed in 2-3 days, and the intestinal digestive enzymes of carnivorous seedlings cannot adapt in a short period of time, resulting in a strong stress response; ② Low survival rate: A survival rate of about 60% means that a large number of seedlings die during the domestication period, which is not suitable for the protective domestication of the rare species Ili bass; ③ No behavioral induction is introduced: Without the guidance of sound or light signals, the seedlings rely entirely on vision and smell to forage, resulting in low feeding aggregation and severe individual differentiation.

[0005] In addition, the 1994 publication by Hebei Fisheries on the method of sound-based feeding training for pond fish describes how sound stimulation is generally used to establish a conditioned reflex for feeding in domestic aquaculture. Applying the principle of conditioned reflexes in animals, objects are struck while feeding, producing simple, rhythmic sounds that travel into the water, allowing the fish to perceive the sound while feeding. After a certain period, a conditioned reflex of "sound → feeding" is formed. The 2012 publication in the Journal of Shanghai Ocean University on the method of sound-based feeding training for black sea bream in net cages describes that the sound training of black sea bream fry generally involves three processes: environmental adaptation, reaching a certain amount of food required, and establishing a conditioned reflex between sound and feeding. The results show that using background noise in conjunction with feeding is an effective method and can convert the black sea bream's short-term sound memory into long-term memory. However, both methods are general operational experiences and do not quantify the acoustic signal parameters and effects for specific fish species.

[0006] In summary, the existing domestication techniques for perch fry generally have the following common defects: (1) Lack of a dedicated domestication program for Ili perch: Existing techniques are all for species such as pikeperch and largemouth bass, and no systematic domestication techniques for Ili perch fry have been disclosed; (2) Lack of a smooth gradient in feed transition: Existing techniques use a "leap" or "stage" transition and do not provide a precise decreasing gradient on a daily basis; (3) Disconnect between acoustic domestication and feed domestication: There is either no acoustic domestication or there is acoustic domestication but it is not linked to the feed gradient; (4) Lack of behavioral quantitative indicators: Only the number of dead fish and the survival rate are recorded, and a behavioral evaluation system such as the first feeding time has not been established. Summary of the Invention

[0007] To address the aforementioned problems, this invention aims to provide a multi-dimensional, low-stress, and efficient domestication method for Ili perch fry, thereby solving the problems of high stress, low survival rate, and uncontrollable water quality in existing similar domestication methods.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A multi-dimensional, low-stress, and efficient domestication method for Ili perch fry includes the following steps: Construct a recirculating aquaculture system for the domestication of Ili perch fry; Ili perch fry are released into a recirculating aquaculture system; Before each feeding, an acoustic conditioned reflex is established in the Ili perch through a tapping sound; Ili perch were fed with a mixture of brine shrimp and commercial feed, following a method of gradually decreasing the amount of brine shrimp each day. Based on the feeding situation, the concentrations of ammonia nitrogen and nitrite in the recirculating aquaculture system are predicted to determine water quality management and control methods. The feeding behavior indicators and growth status of the Ili perch were recorded daily.

[0009] Furthermore, the initial size of the Ili perch is 0.8-1.2 g / fish, and the stocking density of Ili perch fry in the recirculating aquaculture system is 150-200 fish / 1000L.

[0010] Furthermore, the specific operation of establishing acoustic conditioning for Ili perch through tapping sounds includes: tapping for 10 seconds at a frequency of 1 time per second before each feeding, with a sound intensity of about 60-70 decibels.

[0011] Furthermore, the method of gradually decreasing the amount of artemia daily is as follows: Day 1-2: 100% artemia; Day 3: 90%±5% artemia; Day 4: 80%±5% artemia; Day 5: 70%±5% artemia; Day 6: 60%±5% artemia; Day 7: 50%±5% artemia; Day 8: 40%±5% artemia; Day 9: 30%±5% artemia; Day 10: 20%±5% artemia; Day 11: 10%±5% artemia; Day 12: 5%±3% artemia; Day 13-14: 0% artemia.

[0012] Furthermore, the daily feeding rate in the gradual decreasing gradient method for Artemia worms is as follows: 30% on day 1-2, 28% on day 3, 26% on day 4, 24% on day 5, 22% on day 6, 20% on day 7, 20% on day 8, 18% on day 9, 18% on day 10, 16% on day 11, 16% on day 12, and 15% on days 13-14.

[0013] Furthermore, based on feeding conditions, the concentrations of ammonia nitrogen and nitrite in the recirculating aquaculture system are predicted to determine water quality management and control methods, specifically including the following steps: Calculate the daily ammonia nitrogen production in the recirculating aquaculture system based on the daily feeding rates of brine shrimp and commercial feed. Convert the daily ammonia nitrogen production in the recirculating aquaculture system into ammonia nitrogen concentration; Predicting the hysteresis peak value of nitrite based on ammonia nitrogen concentration; Based on the predicted ammonia nitrogen concentration and nitrite lag peak, the water exchange time and volume are determined.

[0014] Furthermore, the method for calculating the daily ammonia nitrogen production in a recirculating aquaculture system is as follows: Total daily ammonia nitrogen production = Artemia ammonia nitrogen contribution + Commercial feed ammonia nitrogen contribution; Artemia nitrogen contribution of Artemia = daily feed amount of Artemia × dry matter ratio of Artemia × crude protein content of Artemia × nitrogen excretion coefficient. Commercial feed ammonia nitrogen contribution = daily feed intake of commercial feed × crude protein content of commercial feed × nitrogen excretion coefficient.

[0015] Furthermore, the specific method for calculating ammonia nitrogen concentration is as follows: Actual ammonia nitrogen concentration on the day = Actual ammonia nitrogen concentration on the previous day + Theoretical increase in ammonia nitrogen on the day - Removal amount by the nitrification system - Dilution amount by water exchange; Theoretical daily increase in ammonia nitrogen = total daily ammonia nitrogen production / system water volume.

[0016] Furthermore, the specific timing and volume of water replacement are as follows: 15-20% of the water should be replaced on the 3rd day; 20-30% of the water should be replaced on the 5th day.

[0017] Furthermore, the feeding behavior indicators include the time of first feeding and the time of end of feeding; the growth status includes survival rate and weight gain rate.

[0018] The beneficial effects of this invention are: 1. The feeding training method for Ili perch fry in this invention forms a dynamic synergistic system with acoustic domestication and food gradient over time. The acoustic signal first establishes a stable conditioned reflex anchor with 100% artichokes on days 1-2. From day 3 onwards, commercial feed is introduced, and the existing sound-feeding reflex provides an attraction to the unfamiliar commercial feed, encouraging the fry to try it. Subsequently, as the proportion of artichokes decreases daily and the proportion of commercial feed increases daily, the acoustic signal continues to exert a behavioral anchoring effect, compensating for the potential loss of attraction due to the withdrawal of artichokes and ensuring stable and consistent feeding behavior throughout the transition period. Experimental data shows that under the same acoustic conditions, the group with food gradient had a commercial feed acceptance rate that increased from 20-30% to 100% compared to the group with only commercial feed. The two are interdependent and synergistic, jointly achieving a low-stress, high-efficiency transition technique.

[0019] 2. The method for domesticating Ili perch fry in this invention achieves a survival rate of ≥95% after 14 days of domestication, which is about 22 percentage points higher than the survival rate of the existing artificial feed domestication method for pikeperch (73.4%), and about 35 percentage points higher than the survival rate of the rapid feeding conversion method for largemouth bass / California bass (about 60%).

[0020] 3. The domestication cycle of the Ili perch fry domestication method in this invention is short, and the entire domestication process can be completed in 14 days, which is more than half the domestication cycle (more than 30 days) of the existing pikeperch artificial feed domestication method.

[0021] 4. This invention also establishes a dynamic monitoring model for ammonia nitrogen / nitrite based on the amount of artichokes fed. The peak ammonia nitrogen level during the acclimatization period was 0.28 mg / L, which is 46% lower than the full-process artichoke scheme (0.52 mg / L). The water quality is stable and controllable, effectively preventing water quality collapse.

[0022] 5. The behavioral domestication effect of the feeding method for Ili perch fry in this invention is significant. Acoustic conditioning reflexes are successfully established on days 3-5. The time for the first feeding is shortened from 45-60 seconds on day 1 to 1-2 seconds on day 14, and the feeding clustering rate reaches 100%.

[0023] 6. This invention provides a complete 14-day gradual decreasing feeding schedule for artemia, a water quality control scheme, and behavioral observation indicators. It can be operated in a standardized manner and the technology is highly reproducible. Attached Figure Description

[0024] Figure 1 This is a flowchart of the multi-dimensional low-stress and high-efficiency domestication method for Ili perch seedlings in this invention; Figure 2 This is a schematic diagram of the external structure of the recirculating aquaculture system in this invention; Figure 3 This is a schematic diagram of the internal structure of the recirculating aquaculture system in this invention; Figure 4 This is a graph showing the trend of water quality indicators during the 14-day acclimatization period in this invention. Figure 5 These are photos of the comparative experiment site in this invention; Figure 6 This is a comparison chart showing the results of the daily decreasing gradient method of brine shrimp quantity, feeding with brine shrimp as the whole, and feeding with commercial feed as the whole in this invention.

[0025] The components include: 1. Recirculating aquaculture pond; 2. Inlet pipe; 3. Drain pipe; 4. Aeration pipe; 5. Feeding platform; 6. Tapping pad; and 7. Shelter pipe. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Example 1: Refer to Appendix Figure 1 As shown, this invention provides a multi-dimensional, low-stress, and efficient domestication method for Ili perch seedlings, specifically including the following steps: Step 1: Construct a recirculating aquaculture system for the domestication of Ili perch fry; See attached document Figure 2 and attached Figure 3 As shown, the recirculating aquaculture system includes a recirculating aquaculture pond 1, which is a cement pond. Specifically, it can be square or any other shape, with a volume of 2000L to meet the needs of large-scale domestication of Ili perch fry.

[0028] The recirculating aquaculture pond 1 is connected to an inlet pipe 2, an outlet pipe 3, and an aeration pipe 4, forming a complete recirculating aquaculture system. The inlet pipe 2 is used to continuously replenish water into the recirculating aquaculture pond 1 to maintain stable water quality. The outlet pipe 3 is used to discharge wastewater and uneaten feed from the recirculating aquaculture pond 1 to achieve water renewal. One end of the aeration pipe 4 is located outside the recirculating aquaculture pond 1, and the other end is located at the bottom of the recirculating aquaculture pond 1. It continuously aerates the water to increase oxygen, ensuring the dissolved oxygen requirements of the Ili perch fry. At the same time, it can also agitate the water through aeration to promote uniform water circulation within the recirculating aquaculture pond 1.

[0029] A feeding platform 5 is provided on one side of the recirculating aquaculture pond 1. The feeding platform 5 is a cement feeding platform, approximately 30cm wide, used for temporary placement of feed for single feedings, not for long-term storage. A tapping pad 6, a 10cm x 10cm rubber tapping pad, is provided on the feeding platform 5 as a sound source device for acoustic acclimatization. The tapping pad 6 can be manually tapped with a wooden stick at a fixed frequency of 1 tap per second, with each tap lasting 10 seconds, producing a sound intensity of approximately 60-70 decibels. Tapping for 10 seconds before each feeding establishes a conditioned reflex of "tapping sound → feeding," thus achieving feeding acclimatization for Ili perch fry. In addition, the sound source device in this invention can also provide acoustic stimulation through various other methods, such as playing specific audio clips using fixed-frequency electronic or underwater speakers.

[0030] The recirculating aquaculture pond 1 is equipped with multiple shielding pipes 7 near the pond wall. The shielding pipes 7 are hollow pipes with open ends, which allow weaker fish to hide, reduce cannibalism, and improve the survival rate and domestication efficiency of the seedlings.

[0031] Step 2: Release the Ili perch fry into the recirculating aquaculture system; In this embodiment, the initial size of the Ili perch was selected as 0.8-1.2 g / fish. The stocking density was 150-200 fish / 1000L (i.e., 150-200 fish / m³). Before stocking, the Ili perch fry were disinfected with a 3% saline bath for 5-10 minutes. In the initial stage after entering the pond, a low-light or full-shade environment was adopted to reduce stress on the fry. It should be noted that in actual operation, the density can be adjusted to 100-150 fish / 1000L (lower density) or 200-250 fish / 1000L (requiring enhanced water quality management) depending on the size of the fry and the carrying capacity of the system, as long as the biomass load is kept within the safe range of ≤1.0 kg / m³ initially and ≤2.0 kg / m³ at the end.

[0032] In addition, the water temperature in the recirculating aquaculture system is controlled at 22±1℃, the pH is controlled at 7.60±0.35 (daily fluctuation ≤0.5), dissolved oxygen is maintained at ≥6.0 mg / L, ammonia nitrogen target is ≤0.1 mg / L, and nitrite target is ≤0.01 mg / L.

[0033] Step 3: Before each feeding, establish an acoustic conditioned reflex for the Ili perch by tapping the sound; In this embodiment, the feeding frequency is 3-6 times per day. During the acclimatization period, the feeding is carried out according to a fixed number of daily feedings to ensure that the number of daily feedings and the feeding time are the same during the acclimatization period.

[0034] Taking feeding four times a day as an example, the times are 09:00, 13:00, 17:00, and 21:00. Before each feeding, the feeder taps the cone at a frequency of 1 time per second for 10 seconds, with a sound intensity of about 60-70 decibels. Immediately after the tapping ends, the bait is scattered to establish a signal-reward relationship of "tapping sound → feeding".

[0035] A fixed-frequency tapping sound is transmitted to the central nervous system through the fish's inner ear bulbar sac and lateral line system, forming a precise temporal pairing with subsequent feeding behavior. After 3-5 days of repeated reinforcement, a stable synaptic connection is established between the auditory center and the feeding center in the fish's brain, forming an anticipatory response of "secreting digestive juices and surfacing to gather upon hearing a sound." Thereafter, whenever a tapping sound is heard, the fish quickly rise from the bottom or hidden places to gather at the feeding area, achieving a swarming feeding frenzy. Studies on the acoustic conditioning of Ili perch show that fish conditioned by sound can convert short-term auditory memory into long-term memory, establishing an acoustic conditioned reflex.

[0036] Step 4: Feed the Ili perch with a mixture of brine shrimp and commercial feed, following a gradual reduction in the amount of brine shrimp per day. During the transition to a different diet in fish, the digestive enzyme system requires a certain amount of time to adjust its gene expression. For carnivorous fish, their digestive system needs to gradually adapt to the plant protein antigens in commercial formulated feeds. Replacing live food with formulated feed significantly affects the digestive and absorptive functions and growth performance of carnivorous fish, requiring them to adapt to the change in diet by altering the activity of their digestive enzymes. If the transition is too rapid, the intestinal digestive enzymes cannot adapt in a short period, leading to digestive disorders and anorexia; if the transition is too slow, the acclimatization period is too long, resulting in water quality deterioration and increased aquaculture costs. Therefore, feed gradient design must find the optimal balance between a "smooth transition" and a "controllable cycle."

[0037] Based on the above principles, the daily decreasing gradient method for Artemia quantity in this invention comprehensively considers the theory of gradient adaptation of intestinal digestive enzyme activity, the morphological development law of the digestive system, and the principles of sensory biology for attracting appetite.

[0038] (1) The theory of gradient adaptation of intestinal digestive enzyme activity This is the core scientific principle supporting the entire daily decreasing gradient method. The digestive enzyme system of carnivorous fish needs to adjust daily when switching from animal-based feed to commercial feed containing plant protein; it cannot mutate. After mandarin fish consume formulated feed, both the structure of their digestive tract and the activity of their digestive enzymes undergo adaptive changes. For carnivorous fish like the Ili perch, the adjustment of enzyme activity in the digestive system requires time. Based on this theory, this invention designs a 14-day gradually decreasing gradient, allowing sufficient time for the fish's digestive enzymes to adjust their gene expression, avoiding digestive disorders and anorexia caused by sudden changes.

[0039] Specifically, the proportion of artichokes is reduced by 5%-20% daily. This rate of change is based on the adaptation cycle of intestinal enzyme activity in carnivorous fish. Studies on the domestication of mandarin fish show that after carnivorous fish consume formulated feed, their digestive enzyme activity (especially amylase and protease) undergoes significant changes, but these changes are gradual and require sufficient time for enzyme system reconstruction. Research indicates that the length of the transition period directly affects the success rate of the transition—if the transition period is short, live feed cannot effectively induce fry to adapt to formulated feed. Based on this principle, the feed gradient of this invention is controlled at a daily variation of 10%-20% in the initial stage (days 3-5), and further slowed to 5%-10% in the middle and later stages (days 6-11), ensuring sufficient adaptation time for the enzyme system.

[0040] (2) Morphological development patterns of the digestive system The digestive system of Ili perch fry is in a rapid development stage. Existing research shows that the activity of digestive enzymes in perch is closely related to the individual developmental stage. At the fry stage, with an initial weight of approximately 1.0 g / fish, their intestinal length, gastric gland development, and digestive enzyme secretion capacity are all limited, making it impossible for them to accept a high proportion of plant protein at once. The gradient design of this invention fully considers the physiological tolerance of the fry's digestive system, allowing sufficient adaptation time by using a lower proportion of commercial feed in the early stages (10%-30%).

[0041] (3) Sensory biological principles of attracting food The aroma and color of brine shrimp have a strong visual and olfactory appeal to Ili perch fry. This invention's gradient design fully utilizes this feeding principle—gradually mixing brine shrimp into commercial feed, using the brine shrimp's feeding signals to drive the intake of the commercial feed. This method has been widely proven effective in the domestication of carnivorous fish such as California bass, and its domestication pathway, which uses a mixture of frozen zooplankton and microparticle-based feed, significantly improves the domestication rate. Studies have shown that the active substances contained in live bait can stimulate growth and enhance appetite, making it an essential food for juvenile aquatic animals.

[0042] After establishing the overall decreasing framework, the specific feeding methods were optimized and adjusted by considering the target setting for different domestication stages (feeding induction period, adaptation period, transition period, conversion period, and consolidation period), the changing pattern of daily feeding rate, and feedback from behavioral indicators such as the duration of each meal. This included the experimental determination of key time nodes, the gradient adjustment of daily feeding rate, and the optimization of feeding frequency.

[0043] I. Determination of key time points in experiments: The key time points of the daily decreasing gradient method for brine shrimp in this invention include the time when commercial feed is first added, the mixing time of brine shrimp:commercial feed = 50:50, and the time when brine shrimp feeding is stopped. For these three key time points, single-factor gradient experiments are carried out respectively, and the optimal parameters are determined by using the survival rate, commercial feed acceptance rate, and first feeding time as evaluation indicators.

[0044] 1. Time when commercial ingredients begin to be added The commercial feed was introduced on days 2, 3, and 4, with three parallel experiments for each introduction time, and all other experimental conditions were the same. The results showed that when commercial feed was introduced on day 2, seedlings refused to eat it because acoustic reflection had not yet been established, resulting in a survival rate of 82.3%. When commercial feed was introduced on day 3, acoustic reflection was initially established, and the acceptance rate of commercial feed gradually increased, resulting in a survival rate of 95.8%. When commercial feed was introduced on day 4, the acclimatization period was extended by 2.0 days, ammonia nitrogen accumulation increased, and the survival rate reached 94.5%. Therefore, day 3 is the optimal time point for the establishment of acoustic reflection and the introduction of commercial feed.

[0045] 2. Mixing time for brine shrimp: commercial feed = 50:50 The artemia:commercial feed ratio of 50:50 was set for days 6, 7, and 8, with three parallel trials for each mixing time, and all other experimental conditions were kept the same. The results showed that from day 6 onwards, with an artemia:commercial feed ratio of 50:50, the feeding activity of the Ili perch decreased, uneaten feed increased by 25%, and the peak nitrite level was 0.030 mg / L (higher than on day 7, presumably due to the increased uneaten feed). From day 7 onwards, with an artemia:commercial feed ratio of 50:50, the feeding behavior of the Ili perch stabilized, and the peak nitrite level was 0.022 mg / L. From day 8 onwards, with an artemia:commercial feed ratio of 50:50, the acclimatization period of the Ili perch was prolonged, the water quality load increased, and the peak nitrite level reached 0.032 mg / L (due to the increased artemia). Therefore, setting the mixing time of artemia:commercial feed at 50:50 on day 7 is optimal, as the digestive system of the Ili perch fry has initially adapted to the commercial feed, representing a critical equilibrium point for the gradient transition.

[0046] 3. End time of brine shrimp harvesting The artichoke feeding was stopped on days 12, 13, and 14, with three parallel trials for each time. All other experimental conditions were the same. Results showed that stopping artichoke feeding on day 12 resulted in some individuals refusing to eat. Stopping artichoke feeding on day 13 did not significantly change the feeding behavior of the Ili perch, and the commercial feed acceptance rate was 100%. Stopping artichoke feeding on day 14 showed no significant difference compared to day 13, but increased the cost of using live bait. Therefore, stopping artichoke feeding on day 13 can shorten the acclimatization period while ensuring a high survival rate.

[0047] II. Gradual Adjustment of Daily Feeding Rate The daily feeding rate gradually decreases from 30% on the first two days (peak feeding period) to 15% on the 13th-14th days (stabilization period for commercial feed).

[0048] In the early stages of domestication (days 1-2), the seedlings showed a very high level of enthusiasm for feeding on artichokes and could tolerate a high feeding rate. In the later stages of acclimatization (after day 7), commercial feed accounts for more than 50% of the feed, and the feeding enthusiasm of the seedlings decreases slightly. Appropriately reducing the feeding rate can reduce uneaten feed and water pollution, while avoiding indigestion caused by overfeeding.

[0049] III. Optimization of Feeding Frequency Because the digestive system of seedlings is not fully developed during the seedling stage, the amount of food they can eat at one time is limited, so they need to be fed "small amounts frequently". Therefore, they are fed 4 times a day (09:00, 13:00, 17:00, 21:00), with an interval of about 4 hours between the 4 feedings, which is consistent with the digestion and emptying cycle of the seedlings. This is consistent with the frequency of the 4 signal reinforcements per day during acoustic acclimatization, so as to form a stable conditioned reflex.

[0050] In summary, the daily decreasing gradient method for artemia in this invention does not randomly reduce the amount of artemia, but rather determines a precise numerical range of the daily percentage of artemia. Specifically: Day 1-2: 100% artemia; Day 3: 90% ± 5% artemia; Day 4: 80% ± 5% artemia; Day 5: 70% ± 5% artemia; Day 6: 60% ± 5% artemia; Day 7: 50% ± 5% artemia; Day 8: 40% ± 5% artemia; Day 9: 30% ± 5% artemia; Day 10: 20% ± 5% artemia; Day 11: 10% ± 5% artemia; Day 12: 5% ± 3% artemia; Day 13-14: 0% artemia.

[0051] In this embodiment, the decreasing method described in Table 1 below can be followed.

[0052] Table 1. Gradual feeding schedule for Ili perch with decreasing daily artichoke quantity over 14 days. Day 1 100% 0% 120.0 0 30% Live bait feeding period Day 2 100% 0% 120.0 0 30% Live bait feeding period Day 3 90% 10% 100.8 11.2 28% early adaptation period Day 4 80% 20% 83.2 20.8 26% Mid-adaptation Day 5 70% 30% 67.2 28.8 24% Late adaptation period Day 6 60% 40% 52.8 35.2 22% early transition period Day 7 50% 50% 40.0 40.0 20% Mid-transition period Day 8 40% 60% 32.0 48.0 20% End of transition period Day 9 30% 70% 21.6 50.4 18% Initial stage of conversion Day 10 20% 80% 14.4 57.6 18% Mid-term transition Day 11 10% 90% 6.4 57.6 16% End of conversion Day 12 5% 95% 3.2 60.8 16% Consolidation period Day 13 0% 100% 0 60.0 15% Complete domestication period Day 14 0% 100% 0 60.0 15% Complete domestication period

[0053] It should be noted that in this embodiment, the brine shrimp are live brine shrimp nauplii (wet weight), and the commercial feed is 0.3mm commercial pellet feed (crude protein ≥45%). As a carnivorous fish, the digestive system of the Ili perch needs to gradually adapt to the plant protein antigens in the commercial feed. The gradual reduction of brine shrimp (5%-20% daily) allows sufficient time for the fish's digestive enzymes to adjust their gene expression, avoiding digestive disorders and anorexia caused by sudden changes. Optionally, the brine shrimp in this invention can also be replaced by frozen adult brine shrimp, frozen copepods, or fragments of tubifex worms, as long as they have a similar odor and visual stimulation to brine shrimp and can serve as a transitional attractant. The commercial feed can be replaced by semi-moist soft pellet feed or microencapsulated feed.

[0054] When feeding, it is important to first divide the total daily feed into 4 equal portions, and then feed each portion at 09:00, 13:00, 17:00, and 21:00 each day (dividing the total daily feed equally according to the feeding frequency, maintaining a daily feeding rate within the range of 15%-30%), avoiding overfeeding at a single time; each feeding should ideally be completed within 20 minutes, following the principle of "small amounts, multiple times"; if the feed is difficult to consume at a certain meal, the proportion of the previous day should be reduced to consolidate for another day; one hour after the last feeding of the day, use a 10 mm diameter siphon to slowly siphon out the dead corners of the pond bottom, removing uneaten feed and feces to avoid agitating the water and causing stress to the seedlings.

[0055] Step 5: Predict the ammonia nitrogen and nitrite concentrations in the recirculating aquaculture system based on feeding conditions, and determine water quality management and control methods; In recirculating aquaculture systems, the main source of ammonia nitrogen is protein from the feed, which enters the water body through metabolic excretion and decomposition of uneaten feed after being ingested by fish. Approximately 16% of the nitrogen in the feed is assimilated by fish for growth, while the remaining approximately 80% is excreted as metabolic waste, of which about 90% is excreted as total ammonia nitrogen (TAN).

[0056] Based on the above theoretical foundation, the formula for calculating the daily ammonia nitrogen production can be derived using the principle of material balance, as follows: Daily ammonia nitrogen production = Daily feed intake × Feed protein content × Nitrogen excretion coefficient The nitrogen excretion coefficient takes into account factors such as the nitrogen content in protein (approximately 16%), nitrogen assimilation rate (approximately 20%), and the proportion of TAN in excreted nitrogen (approximately 90%), with a typical value of 0.092. Based on this formula, and combined with the daily feeding data of Artemia and commercial feed in Table 1 above, the theoretical input of ammonia nitrogen in the recirculating aquaculture system can be calculated daily.

[0057] After calculating the theoretical input of ammonia nitrogen in the recirculating aquaculture system, it is also necessary to consider the conversion and removal of ammonia nitrogen by the nitrification system. The sources of the nitrification system include three aspects: (1) Nitrifying bacteria naturally exist in the aquaculture water (groundwater or surface water), which will enter the recirculating aquaculture system after aeration and filtration; (2) Symbiotic nitrifying bacteria also exist in the mucus on the body surface and intestines of Ili perch fry, which will be brought into the system with the fry; (3) During the acclimatization period from the 3rd to the 7th day, as the ammonia nitrogen concentration increases, nitrite bacteria multiply rapidly at a rate of about one generation every 24 hours, accounting for more than 80% of the total nitrifying bacteria in the system after the 7th day, becoming the dominant bacteria. Nitrification is a two-step continuous reaction process in which ammonia nitrogen (NH3-N) is converted into nitrite by nitrite bacteria, and then converted into nitrate by nitrate bacteria. Since the proliferation rate of nitrite bacteria is slower than the ammonia nitrogen production rate, the nitrification system has insufficient processing capacity in the early stage of acclimatization, which will lead to the accumulation of ammonia nitrogen and the appearance of a peak; while the peak of nitrite usually lags behind the peak of ammonia nitrogen by about 2 days. This nitrification kinetics is key to predicting nitrite trends. Based on theoretical calculations, calibration and verification were performed using actual operating data from a 2000L circulating water system.

[0058] More specifically, this step includes the following sub-steps: Sub-step 501: Calculate the daily ammonia nitrogen production of the recirculating aquaculture system based on the daily feeding amounts of brine shrimp and commercial feed; in: Artemia nitrogen contribution (g) from Artemia = Daily feed amount of Artemia (g, wet weight) × Artemia dry matter ratio × Artemia crude protein content × Nitrogen excretion coefficient Commercial feed ammonia nitrogen contribution (g) = Daily feed intake (g, dry weight) × Crude protein content of commercial feed × Nitrogen excretion coefficient Total daily ammonia nitrogen production (g) = Ammonia nitrogen contribution from Artemia + Ammonia nitrogen contribution from commercial feed Because artichokes are live feed (moisture content approximately 90-95%), their dry matter and crude protein content are much lower than those of commercial compound feeds (crude protein ≥45%). Therefore, when the feeding weight is the same, the actual ammonia nitrogen contribution of artichokes is lower than that of commercial feed. Consequently, ammonia nitrogen did not reach its peak when the amount of artichokes fed was at its maximum on the first two days of feeding, but instead continued to rise after commercial feed was added on the third day.

[0059] Step 502: Convert the daily ammonia nitrogen production of the recirculating aquaculture system into ammonia nitrogen concentration; More specifically, when converting ammonia nitrogen concentration, it is necessary to first calculate the theoretical increase in ammonia nitrogen per day, and then calculate the actual ammonia nitrogen concentration for the current day based on the ammonia nitrogen concentration of the previous day.

[0060] in: Theoretical daily increase in ammonia nitrogen (mg / L) = Total daily ammonia nitrogen production (mg) / System water volume (L) Actual ammonia nitrogen concentration on the day (mg / L) = Actual ammonia nitrogen concentration on the previous day + Theoretical increase in ammonia nitrogen on the day - Removal capacity of the nitrification system - Dilution capacity of water exchange In the formula, the removal capacity of the nitrification system depends on the maturity of the biofilter. In the early stage of acclimatization (days 1-3), the nitrification system is not yet fully established and the removal capacity is weak; as acclimatization progresses (after day 4), nitrifying bacteria gradually proliferate, and the removal capacity gradually increases.

[0061] Based on the above calculation formula and the daily decreasing trend of brine shrimp in this invention, the results of the ammonia nitrogen concentration calculation are shown in the appendix. Figure 4 As shown, the ammonia nitrogen concentration reached 0.28 mg / L on the 3rd day.

[0062] Step 503: Predict the hysteresis peak value of nitrite based on ammonia nitrogen concentration; Ammonia nitrogen is oxidized to nitrite by nitrite-oxidizing bacteria, which is a biochemical process with a time lag. Based on the principle of nitrification kinetics, the nitrite concentration can be approximately equal to the rate of increase in ammonia nitrogen concentration over the previous 1-2 days minus the oxidation rate of nitrite-oxidizing bacteria. Therefore, the time of nitrite peak appearance is approximately equal to the time of ammonia nitrogen peak appearance plus 2 days.

[0063] Because nitrifying bacteria multiply more slowly than ammonia-oxidizing bacteria, nitrite will continue to accumulate in the early stages of acclimatization, only beginning to decrease once the number of nitrifying bacteria is sufficient. (See attached...) Figure 3 As can be seen, nitrite reached 0.030 mg / L on day 5, which was 2 days later than the peak of ammonia nitrogen on day 3.

[0064] Step 504: Determine the water exchange time and volume based on the predicted ammonia nitrogen concentration and nitrite hysteresis peak value.

[0065] Based on the tolerance of Ili perch fry to ammonia nitrogen and nitrite, when the predicted ammonia nitrogen concentration exceeds the safety threshold (0.1 mg / L), or the predicted nitrite concentration exceeds the safety threshold (0.01 mg / L), the recirculating aquaculture system needs to undergo a water exchange. The formula for calculating the water exchange volume is: Water exchange rate (%) = Theoretical water exchange rate × Stress correction factor × Nitrification system correction factor + Safety redundancy =[(Predicted concentration - Safety threshold) ÷ Predicted concentration × 100%] × Stress correction factor × Nitrification system correction factor + Safety redundancy The basic theoretical water exchange volume reflects the theoretical water exchange volume required to reduce water quality to a safe threshold. The predicted concentrations include ammonia nitrogen concentration and nitrite concentration; Stress correction factor: 0.2-0.3 is used to address the high sensitivity of Ili perch fry to changes in the aquatic environment (to avoid stress caused by temperature differences and water quality fluctuations due to large water changes). Nitrification system correction factor: reflects the dynamic change of the system's nitrification capacity. In the early stage of acclimatization (days 1-5), the nitrification system is immature, and the value is 0.8-0.9. In the middle and late stages of acclimatization (days 6-14), the nitrification system is gradually established, and the value is 0.5-0.7. Safety redundancy: A value of 5-10% is used to offset prediction errors and sudden water quality fluctuations.

[0066] On day 3, the predicted ammonia nitrogen concentration reached 0.28 mg / L, exceeding the safety threshold of 0.1 mg / L. Based on the formula above, the theoretical water exchange rate was approximately 64% ((0.28-0.1) / 0.28×100%≈64%). However, considering the Ili perch's sensitivity to changes in the aquatic environment and the gradual establishment of the nitrification system, the water exchange rate was adjusted. The final calculated water exchange rate was approximately 21% (64%×0.25 (stress correction)×0.85 (nitrification correction)+7% (safety redundancy)≈21%). In actual operation, a conservative control strategy was adopted, keeping the water exchange rate between 15-20% to control risk and avoid temperature stress caused by excessive water exchange. On day 5, when nitrite reached 0.030 mg / L, again based on the principle of balancing risk and stress, a water exchange of 20-30% was recommended.

[0067] By actively exchanging water on day 3 (peak ammonia nitrogen period) and day 5 (peak nitrite period), the water quality indicators were kept within a controllable range near the safe threshold of Ili perch (ammonia nitrogen ≤ 0.1 mg / L, nitrite ≤ 0.01 mg / L).

[0068] In this embodiment, the water quality prediction and control during the 14-day acclimatization period of the Ili perch is shown in Table 2 below.

[0069] Table 2. Water quality prediction and control during the 14-day acclimatization period of Ili perch (2000L system) Day 1 120.0 0.15 0.008 6.8 7.75 Normal vacuuming Day 2 120.0 0.22 0.012 6.7 7.72 Normal vacuuming Day 3 100.8 0.28 0.018 6.5 7.68 Change 15-20% of the water (approximately 300-400L). Day 4 83.2 0.25 0.025 6.6 7.65 Reduce the amount of feed by 10% Day 5 67.2 0.20 0.030 6.7 7.63 Change 20-30% of the water. Day 6 52.8 0.15 0.028 6.8 7.62 Normal vacuuming Day 7 40.0 0.10 0.022 6.9 7.60 Water quality has entered a safe range Day 8 32.0 0.08 0.022 7.0 7.58 Normal vacuuming Day 9 21.6 0.06 0.025 7.1 7.57 Normal vacuuming Day 10 14.4 0.05 0.022 7.2 7.56 Normal vacuuming Day 11 6.4 0.05 0.020 7.2 7.55 Change 20-30% of the water. Day 12 3.2 0.04 0.008 7.3 7.55 Normal vacuuming Day 13 0 0.04 0.006 7.3 7.56 Normal vacuuming Day 14 0 0.04 0.006 7.4 7.55 Domestication complete, system stable Step 6: Record the feeding behavior indicators and growth status of the Ili perch daily.

[0070] Specifically, the feeding behavior indicators include the time of first feeding and the time of end of feeding; First feeding time: the time (in seconds) between the first fish taking its first bite and the feeding; this indicator reflects the speed at which acoustic conditioning is established.

[0071] Feeding end time: The time (in minutes) during which all fish stop eating; this indicator reflects feeding activity and the intensity of competition for food.

[0072] The growth data includes survival rate and weight gain rate; The number of dead fish was recorded daily, and the survival rate was calculated at the end of the experiment. Survival rate = final number of surviving fish / initial number of fish stocked × 100%.

[0073] Thirty fish were sampled before and after the domestication process began and weighed to calculate initial weight, final weight, weight gain rate, and specific growth rate (SGR).

[0074] The initial weight (g / tail) is the arithmetic mean of the weights of 30 healthy seedlings randomly selected before the start of acclimatization, weighed one by one using an electronic balance (accuracy 0.01g).

[0075] The final weight (g / tail) is the arithmetic mean obtained by randomly selecting 30 surviving seedlings and weighing them one by one using the same method after the domestication was completed.

[0076] The weight gain rate (WGR, %) is calculated as follows: WGR = ((final weight - initial weight) / initial weight) * 100%.

[0077] The specific growth rate (SGR, % / d) is calculated as follows: SGR = ((ln(final weight) - ln(initial weight)) / acclimatization days) * 100%.

[0078] In this embodiment, the feeding behavior indicators of the Ili perch during the 14-day domestication period are shown in Table 3 below.

[0079] Table 3. Feeding behavior indicators of Ili perch during the 14-day acclimatization period (400 per pond) Day 1 47 27 Unfamiliar with the new environment, acoustic signals have not yet been established. Day 2 42 20 Start to adapt to the feeding rhythm Day 3 28 16 Acoustic conditioned reflexes begin to form Day 4 19 16 With commercial elements added, some individuals are beginning to accept it. Day 5 10 12 Conditioned reflexes are reinforced, and commercial acceptance rates are rising. Day 6 3 11 The group's behavior of grabbing food was obvious. Day 7 3 11 A 1:1 mixing ratio indicates key nodes are functioning normally, and feeding is generally normal. Day 8 2 6 Commercial feed accounted for more than brine shrimp. Day 9 3 6 feeding near full capacity Day 10 2 5 Primarily made of commercial materials, with stable acoustic reflection. Day 11 2 4 The whole pond was scrambling for food Day 12 3 4 Artemia serve only as a feeding signal Day 13 2 4 Commercially available materials, domestication basically complete. Day 14 2 4 Once domestication is complete, acoustic conditioned reflexes are fully established.

[0080] In this comparative experiment, the daily decreasing gradient method of the brine shrimp population of this invention was compared with the feeding methods in patent applications No. 201410149678.6 and No. 201810791084.3 mentioned in the background art. The comparative experimental photos are attached. Figure 5 As shown.

[0081] Group setup: Five parallel experiments were set up: experimental group (following the 14-day gradual decreasing feed of brine shrimp and commercial feed as described in this invention), control group 1 (followed by 100% live brine shrimp for 14 days, with the same daily feeding rate as the experimental group), control group 2 (followed by 100% 0.3mm commercial pellet feed for 14 days, with the same daily feeding rate as the experimental group), control group 3 (following the feeding method described in patent application No. 201410149678.6), and control group 4 (following the feeding method described in patent application No. 201810791084.3); each group had three replicate tanks (2000L circulating water system), with completely identical initial conditions. (1) Seedling specifications: 0.8-1.2g / fish, stocking density 400 fish / pond; (2) Environmental parameters: water temperature 22±1℃, dissolved oxygen ≥6.0mg / L, pH 7.6±0.35; (3) Acoustic conditions: The entire process uses a knocking sound of 1 time / second and 60-70 decibels, and knocks for 10 seconds before each feeding.

[0082] The domestication results for five methods without providing feeding were statistically analyzed, and the results are shown in Table 4 below.

[0083] Table 4. Domestication results of different feeding methods Applicable fish species Ili perch Ili perch Ili perch pikeperch Largemouth bass Domestication cycle 14 days 14 days 14 days More than 30 days 2-3 days Survival rate ≥95% <70% (due to water quality) <50% Approximately 73.4% Approximately 60% First feeding time on day 14 1-2 seconds 2-3 seconds 40-80 seconds Unreported Unreported Commercial acceptance rate 100% - 20-30% 100% (after 30 days) 60-80% Peak ammonia nitrogen levels during the acclimatization period (mg / L) 0.28 0.52 0.14 Unreported Unreported Peak nitrite levels during the acclimatization period (mg / L) 0.030 0.048 0.016 Unreported Unreported Feed transition Daily continuous gradient - - Four-stage leapfrog development Four-way quick replacement Acoustic domestication Fixed throughout have have Only tap 320 lightly on days 3-7. none Water quality monitoring model have none none none none Behavioral quantitative evaluation have none none none none With all other domestication conditions remaining the same, the comparison results of the daily decreasing gradient method of Artemia elegans population with the first feeding time, commercial feed acceptance rate, peak ammonia nitrogen, and peak nitrite levels for both Artemia elegans and commercial feed throughout the entire domestication process are shown in Table 5 and Appendix 6. Figure 6 As shown. The commercial feed acceptance rate is calculated as (number of fish that ate the commercial feed / total number of fish observed) * 100%. This value is calculated based on the number of fish feeding. When feeding, the fish will gather near the feeding point. Fish that do not eat the commercial feed will be in corners or at the edge of the pond, far away from the feeding point. The number of fish that do not eat the commercial feed can be counted directly.

[0084] Table 5. Comparison of first feeding time, commercial feed acceptance rate, peak ammonia nitrogen, and peak nitrite levels for different feeding methods. From Table 5 and Appendix Figure 6 It can be seen from this: Regarding the initial feeding time: the average initial feeding time using the daily decreasing gradient method of artichoke feeding as described in this invention was 2 seconds, which was no different from the group fed with artichokes throughout the entire feeding period (average 3 seconds). However, the average initial feeding time of the group fed with commercial feed throughout the entire feeding period reached 65 seconds, significantly higher than the previous two groups. This is because the combination of acoustic acclimatization and feed gradient in this invention enables the seedlings to reach a feeding response speed to commercial feed that is comparable to that of live bait. The group fed with commercial feed throughout the entire feeding period, lacking live bait enticement and gradient adaptation, could not establish an effective feeding conditioned reflex, resulting in a slow feeding response.

[0085] Regarding the acceptance rate of commercial feed: the acceptance rate of commercial feed using the daily decreasing gradient method of brine shrimp in this invention was 100%, while the acceptance rate of commercial feed in the group fed commercial feed throughout the entire feeding period was only 24.7%. This is because the smooth daily feed gradient allows the seedlings' digestive system to gradually adapt to the plant protein in the commercial feed, while the acoustic signal continues to exert a behavioral anchoring effect, compensating for the lack of feeding attraction after the brine shrimp are removed. Direct feeding of commercial feed will lead to digestive disorders and refusal to eat in the seedlings, and most individuals cannot adapt.

[0086] Regarding peak ammonia nitrogen levels: the peak ammonia nitrogen level in the group fed entirely with artemia was 0.52 mg / L, while the peak ammonia nitrogen level using the gradual reduction method of artemia feeding as described in this invention was only 0.28 mg / L, a 46% reduction compared to the group fed entirely with artemia. The group fed entirely with commercial feed had the lowest peak ammonia nitrogen level, reaching 0.14 mg / L. This is because the group fed entirely with artemia had a large amount of live feed, resulting in more uneaten feed and metabolic waste, leading to severe ammonia nitrogen accumulation; while the group fed entirely with commercial feed had a low feed intake, resulting in low ammonia nitrogen emissions, but extremely low survival rates. Therefore, the feeding method in this invention, while ensuring high feed intake and survival rates, significantly reduces water quality load by gradually reducing the amount of artemia fed.

[0087] Regarding the peak nitrite concentration: the peak nitrite concentration in the group fed with only Artemia was 0.048 mg / L, while the peak nitrite concentration using the daily decreasing gradient method of Artemia feeding as described in this invention was only 0.030 mg / L, a reduction of 37.5% compared to the group fed with only Artemia. The group fed with only commercial feed had the lowest peak nitrite concentration, reaching 0.016 mg / L. This is because the peak nitrite concentration lags behind the peak ammonia nitrogen concentration by 2 days, which conforms to the nitrification kinetics. The feeding method of this invention, by predicting the peak nitrite concentration and precisely changing the water on the 5th day, controls it near the safe threshold (≤0.01 mg / L) for Ili perch, thus avoiding fry mortality caused by nitrite poisoning.

[0088] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A multi-dimensional, low-stress, and efficient domestication method for Ili perch fry, characterized in that, Includes the following steps: Construct a recirculating aquaculture system for the domestication of Ili perch fry; Ili perch fry are released into a recirculating aquaculture system; Before each feeding, an acoustic conditioned reflex is established in the Ili perch through a tapping sound; Ili perch were fed with a mixture of brine shrimp and commercial feed, following a method of gradually decreasing the amount of brine shrimp each day. Based on the feeding situation, the concentrations of ammonia nitrogen and nitrite in the recirculating aquaculture system are predicted to determine water quality management and control methods. The feeding behavior indicators and growth status of the Ili perch were recorded daily.

2. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch seedlings according to claim 1, characterized in that, The initial size of the Ili perch is 0.8-1.2 g / fish, and the stocking density of Ili perch fry in the recirculating aquaculture system is 150-200 fish / 1000L.

3. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch seedlings according to claim 1, characterized in that, The specific steps for establishing acoustic conditioning on Ili perch through tapping include: tapping for 10 seconds at a frequency of 1 time per second before each feeding, with a sound intensity of about 60-70 decibels.

4. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch seedlings according to claim 1, characterized in that, The specific method for gradually decreasing the amount of artemia is as follows: Day 1-2: 100% artemia; Day 3: 90%±5% artemia; Day 4: 80%±5% artemia; Day 5: 70%±5% artemia; Day 6: 60%±5% artemia; Day 7: 50%±5% artemia; Day 8: 40%±5% artemia; Day 9: 30%±5% artemia; Day 10: 20%±5% artemia; Day 11: 10%±5% artemia; Day 12: 5%±3% artemia; Day 13-14: 0% artemia.

5. The multi-dimensional, low-stress, and efficient domestication method for Ili perch seedlings according to claim 4, characterized in that, The daily feeding rate in the gradual decreasing gradient method for Artemia worms is as follows: 30% on day 1-2, 28% on day 3, 26% on day 4, 24% on day 5, 22% on day 6, 20% on day 7, 20% on day 8, 18% on day 9, 18% on day 10, 16% on day 11, 16% on day 12, and 15% on days 13-14.

6. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch fry according to claim 1, characterized in that, Based on feeding data, the concentrations of ammonia nitrogen and nitrite in the recirculating aquaculture system are predicted to determine water quality management and control methods. This includes the following steps: Calculate the daily ammonia nitrogen production in the recirculating aquaculture system based on the daily feeding rates of brine shrimp and commercial feed. Convert the daily ammonia nitrogen production in the recirculating aquaculture system into ammonia nitrogen concentration; Predicting the hysteresis peak value of nitrite based on ammonia nitrogen concentration; Based on the predicted ammonia nitrogen concentration and nitrite lag peak, the water exchange time and volume are determined.

7. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch seedlings according to claim 6, characterized in that, The method for calculating the daily ammonia nitrogen production in a recirculating aquaculture system is as follows: Total daily ammonia nitrogen production = ammonia nitrogen contribution from Artemia + ammonia nitrogen contribution from commercial feed; Artemia nitrogen contribution of Artemia = daily feed amount of Artemia × dry matter ratio of Artemia × crude protein content of Artemia × nitrogen excretion coefficient. Commercial feed ammonia nitrogen contribution = daily feed intake of commercial feed × crude protein content of commercial feed × nitrogen excretion coefficient.

8. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch seedlings according to claim 7, characterized in that, The specific method for calculating ammonia nitrogen concentration is as follows: Actual ammonia nitrogen concentration on the day = Actual ammonia nitrogen concentration on the previous day + Theoretical increase in ammonia nitrogen on the day - Removal amount by the nitrification system - Dilution amount by water exchange; Theoretical daily increase in ammonia nitrogen = total daily ammonia nitrogen production / system water volume.

9. A multi-dimensional, low-stress, and efficient domestication method for Ili perch seedlings according to claim 8, characterized in that, The specific timing and volume of water replacement are as follows: replace 15-20% of the water on the 3rd day; replace 20-30% of the water on the 5th day.

10. The method for multi-dimensional, low-stress, and efficient domestication of Ili perch fry according to claim 1, characterized in that, The feeding behavior indicators include the time of first feeding and the time of end of feeding; the growth status includes survival rate and weight gain rate.

Images