Method for marking rough of low salinity pond sea bass fry

Abstract

The application discloses a method for marking up sea bass fry in a low-salinity pond, which comprises the following steps: cleaning the bottom of the pond, removing sundries and pond bottom water, and then adding water to an appropriate water depth; performing early-stage regulation and treatment on the water quality of the pond before fry is added, wherein the pH of the water body is between 7.8 and 8.3, ammonia nitrogen is 0, nitrite is less than or equal to 0.10, dissolved oxygen is greater than or equal to 7.5 at a water depth of 1 m under the condition that an oxygenator is fully opened, salinity is less than or equal to 7 ppt, water temperature is greater than or equal to 15 DEG C, total alkalinity is 120-150 ppm, hardness is 800-1000 ppm, and transparency is 50 cm to 80 cm; after the fry is added, fish group health care is performed by using a spraying method in a feeding area, and the spraying formula is as follows: formula 1 (100 g of 98% feed-grade Vc, 850 g of glucose and 50 g of 0.3% St. John's wort extract), and formula 2 (100 g of 98% feed-grade Vc, 820 g of glucose and 80 g of hawthorn (200 mesh ultrafine grinding)). By using the method, the survival rate and growth speed of sea bass fry in a low-salinity pond can be improved without changing the current production basic elements and process, so that the sea bass fry basically reaches or exceeds the average marked fry level in the Bajiao sea bass dominant production area in Zhuhai, Guangdong.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aquaculture, in particular to a method for rough marking of sea bass fry in a low salinity (spring water salinity ≤7 ppt) pond. BACKGROUND

[0002] In the past two decades, sea bass pond-scale aquaculture has developed rapidly, especially in the brackish water area between rivers and seas, the yield of pond-scale aquiculture has increased year by year. For example, in Bajiao, Zhuhai, Guangdong, artificial pond aquaculture of sea bass has accounted for more than half of the national output, and the annual output has reached more than 30 billion in recent years, becoming a local dominant characteristic industrial project. However, with the increase of scale aquaculture, the pond aquaculture area in the Bajiao area of the dominant production area is facing saturation, and the industry urgently needs to be extended. However, there is little sea bass aquaculture in the Pingsha area of the Zhuhai Jinwan a few dozen kilometers away. The main reason is that the water salinity in this area is higher than that in the Bajiao area, and the spring water salinity is mostly 5-9 ppt, while that in the Bajiao area is mostly about 0-3 ppt.

[0003] Sea bass fry marking refers to the process of putting small-sized sea bass fry into a pond with a relatively good environment to cultivate them to a certain size, which aims to improve the survival rate of fry and shorten the time of rearing; at the same time, the survival rate of large fry (intermediate cultivated) is relatively stable, which is convenient for the management and scientific feeding of rearing. Most of the existing industrial chain sea bass fry are sourced from Fujian and other places, and the water in the fry pond has been desalinated to 0 ppt several times before hatching. The cultivation and marking technology of sea bass fry sold from Fujian and other places to Guangdong has been developed for many years and is mainly matched for the Bajiao area of Zhuhai; the sea bass fry marking technology in the ponds of the Bajiao area of Zhuhai is quite mature, and the use of disinfection and pond detoxification, multi-vitamin and other traditional Chinese medicine compound drugs for oral administration, reduction or even stop of feeding in adverse weather, micro-ecological preparations, and addition or subtraction of water, etc. are comprehensive methods. However, due to the higher water salinity in the Pingsha area of Zhuhai than in the Bajiao area, the success rate of using this method in sea bass fry marking in the Pingsha area of Zhuhai Jinwan is difficult to reach the level of Bajiao, resulting in few sea bass aquaculture in this area in the past 10 years. SUMMARY

[0004] To solve the problems existing in the prior art, the main purpose of the present application is to provide a method for marking sea bass fry in a low salinity (spring water salinity ≤7 ppt) pond, which can improve the survival rate and growth rate of pond marking fry in low salinity areas, so as to basically reach or exceed the average marking fry level in the dominant production area.

[0005] In order to achieve the above main purpose, the present application discloses a method for marking sea bass fry in a low salinity pond, comprising:

[0006] cleaning the bottom of the pond, removing debris, removing pond bottom water, and then filtering the water to an appropriate depth;

[0007] Before stocking, the pond water quality is pre-treated and adjusted. After adjustment, the pH of the water is between 7.8 and 8.3, ammonia nitrogen is 0, nitrite is ≤0.10, dissolved oxygen at a depth of 1m with the aerator running at full capacity is ≥7.5, salinity is ≤7ppt, water temperature is ≥15℃, total alkalinity is 120-150ppm, hardness is 800-1000ppm, and transparency is 50-80cm.

[0008] After stocking, the fish were given health care by sprinkling the solution in the feeding area. The sprinkling formulas were: Formula 1 [100g of 98% feed-grade vitamin C + 850g of glucose + 50g of 0.3% hypericin extract], and Formula 2 [100g of 98% feed-grade vitamin C + 820g of glucose + 80g of hawthorn (200 mesh ultrafine powder)]. Formulas 1 and 2 were used separately. Formula 1 was used for the first sprinkling, and the interval between fish health care treatments was ≥20 days.

[0009] Furthermore, before the first feeding after seedling introduction, the formula 1 is applied to the feeding area by spraying, and after seedling screening or in special weather conditions, the formula 2 is applied to the feeding area by spraying.

[0010] Furthermore, both Formula 1 and Formula 2 are prepared and used immediately at a dosage of 500g / mu.

[0011] Furthermore, the initial treatment method for pond water quality regulation is as follows: First, use 10 kg / mu / meter water depth of bleaching powder and 30 g / mu / meter water depth of 10% Sophora flavescens extract for disinfection and pest control. Then, after 5-7 days, use EM bacteria or granular Bacillus products to improve the bottom. After 3-5 days of bottom improvement, detoxify the water.

[0012] Furthermore, 24 hours before the arrival of the fish fry, 20cm of the bottom water in the water body that has undergone preliminary conditioning treatment was removed. The water body was disinfected 12-16 hours later. 0.5 hours before the fry were introduced, 50g of 98% feed-grade vitamin C and 450g of glucose per mu (meter of water depth) were sprayed throughout the pond.

[0013] Furthermore, during the seedling stage, no water disinfection or detoxification treatment is carried out except for seed screening, and the aerator is run continuously for 24 hours. During rainfall, 10-20cm of bottom water is pumped out, and no additional water is added during high temperatures. Water is replaced by natural evaporation and natural rainfall. Water management mainly focuses on algae cultivation and fertilization. Lime particles are mainly used to adjust transparency, zeolite powder and / or dolomite powder are used to adjust turbidity, and glucose, brown sugar, phosphate fertilizer, urea and / or potassium fertilizer are used to fertilize the water.

[0014] Furthermore, during the coagulation period, ensure that dissolved oxygen ≥ 7.5, no ammonia nitrogen, nitrite ≤ 0.1, and pH value not exceeding 8.5 at a water depth of 1m with the aerator fully running.

[0015] Furthermore, when selecting a pond area of ​​3-5 mu, the pond is divided into 3 zones: the main stocking zone, the seedling screening and diversion zone, and the main water control zone. The main water control zone is located downwind, and the main stocking zone is located between the seedling screening and diversion zone and the main water control zone. Each zone is separated by a net. Paddlewheel aerators are installed in the seedling screening and diversion zone and the main stocking zone, and a waterwheel aerator is installed in the main water control zone to achieve water circulation. A bottom collection area is also set up in the main water control zone to extract bottom water.

[0016] Furthermore, only one screening is arranged during the brooding period. The screening is carried out 35-40 days after the initial stocking. After screening, the larger fish are transferred to the screening and distribution area, while the smaller fish are kept in the main stocking area.

[0017] Furthermore, when the seedling size is between 2.5cm and 3cm, the seedling density in the seedling area should be controlled at ≤40,000 seedlings / acre, preferably around 30,000 seedlings / acre.

[0018] The technical solution of the present invention has the following beneficial effects:

[0019] This invention provides a method for raising sea bass fry in low-salinity ponds (spring water salinity ≤7ppt). This method can improve the survival rate and growth rate of fry in low-salinity ponds without significantly changing the current basic production elements and processes, so that it can basically reach or exceed the average fry level of advantageous production areas, greatly increasing the area of ​​sea bass pond farming in Zhuhai and promoting the efficient development of the industry. Attached Figure Description

[0020] Figure 1a and 1b This is a zoning structure diagram of the two optional sea bass fry nursery ponds of the present invention;

[0021] Figure 2 This is a schematic diagram of the layout of the aerator and water pump in the pond in an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the placement location of water-regulating inputs in a pond according to an embodiment of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments, but these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0024] This invention provides a method for raising sea bass fry in low-salinity ponds (spring water salinity ≤7ppt). The method includes: selecting a fry raising pond, organizing and laying out the pond, installing and managing facilities, conducting overall water quality analysis and early-stage control management, and managing fish health.

[0025] Furthermore, select a pond of suitable size for fry rearing, controlling the stocking density to ≤40,000 fry / acre, preferably around 30,000 fry / acre. For initial stocking of more than 30,000 fry, a pond of 3-5 acres in size, oriented east-west or north-south, with an effective depth of 2.5-3 meters is generally suitable.

[0026] Furthermore, the pond bottom should be prepared, sloping from east to west or south to north at a gradient of 1-2 degrees. For example... Figure 1a and 1b As shown, the collection area 5 for pumping bottom water can be set in the northwest or northeast corner. The collection area 5 is generally 20-30cm lower than the bottom of the pond, with a collection area of ​​4m x 6m. A 1.5kV portable 2-inch submersible pump is installed in the collection area 5.

[0027] Furthermore, when the fry pond is 3-5 mu (approximately 0.2-0.3 hectares), it can be divided into three sections, with the middle section being smaller and the two outer sections larger. Generally, the middle section occupies 1 / 4 of the entire pond, and the remaining portion is divided equally between the two outer sections. For example... Figure 1a and 1b As shown, the pond is divided into three zones from east to west or from south to north: Zone 1 is the seedling screening and distribution zone, Zone 2 is the main seedling feeding zone, and Zone 3 is the main water control zone. After screening, larger seedlings are assigned to Zone 1, and smaller seedlings are kept in Zone 2. A 3.2-meter-high net with a mesh size of approximately 20 is used to separate the zones. A 40cm x 30cm (depth x width) trench is dug at the bottom of the pond to bury the net, and 3.5m-high bamboo is used for reinforcement at 40cm intervals, with the bamboo inserted 0.5m deep and 3m high.

[0028] Furthermore, one aerator is installed in each area. Preferably, a paddlewheel aerator 6 is installed in areas 1 and 2, positioned in the middle; a waterwheel aerator 4 is installed in area 3, preferably located in the southwest of area 3 (east-west oriented pond, see...). Figure 1a ) or northwest (north-south oriented pond, see Figure 1b The aerators are configured with a basic power of 1.5KV per acre of pond surface, achieving a three-zone large circulation and a whole-pond small circulation (such as...). Figure 2 (As shown).

[0029] Furthermore, the pond should be thoroughly cleaned, removing debris and bottom water. Then, the water should be filtered through an 80-100 mesh screen to a depth of 1.8-2.0 meters. Current river water can be used. Statistics from the past two years show that the salinity of water in the Pingsha area is generally ≤7 ppt, pH ≤8.8, ammonia nitrogen ≤0.6, nitrite ≤0.2, total alkalinity 120-150 ppm, and total hardness between 800-1000 ppm.

[0030] Further, preliminary water quality control measures are implemented in the pond: First, bleaching powder (10 kg / mu / meter depth) and 10% Sophora flavescens extract (30 g / mu / meter depth) are used for disinfection and pest control. After 5-7 days, EM bacteria or granular Bacillus products are used according to instructions to improve the pond bottom. 3-5 days after bottom improvement, the water is detoxified, and 5 days later, the water is tested. After control, the pH is generally between 7.8 and 8.3, ammonia nitrogen is 0, nitrite is ≤0.1, dissolved oxygen at a depth of 1 meter with aerators running at full capacity is ≥7.5, salinity is ≤7 ppt, water temperature is ≥15℃, total alkalinity is 120-150 ppm, hardness is 800-1000 ppm, and transparency is 50-80 cm. If the water transparency is not ideal, lime granules can be used for adjustment, generally at a dosage of 2-3 kg / mu / meter depth, to maintain overall fertility and vitality in the water. Aeration is maintained continuously for 24 hours during the disinfection period.

[0031] like Figure 3 As shown, the water conditioning inputs are placed at designated point 7 in the pond, with 60% placed in the main water conditioning control area 1, and the remainder placed in the seedling diversion area 1 and the main seedling area 2 respectively; preferably, the water conditioning inputs are placed in an L-shaped or U-shaped open manner, without forming a closed loop or full pond placement.

[0032] Furthermore, 24-48 hours after the fish fry arrive, pump 20cm of bottom water from the previously treated water body. 12-16 hours later, disinfect the water body. Specifically, use 300ml / mu / meter of 10% povidone-iodine for disinfection. 0.5 hours before the fry are introduced, treat the entire pond with 50g of 98% feed-grade vitamin C and 450g / mu / meter of glucose.

[0033] Furthermore, select fry with high uniformity between 2.5cm and 3cm and release them before 8:00 AM. The fry can be sourced from current supply channels and no further treatment is required. For fry transported within 6 hours, feed them that afternoon; for those transported more than 6 hours, feed them the following morning, ideally within 36 hours. Feed the fish twice daily, according to their body weight. Before the first feeding, apply a mixture of Formula 1 (100g of 98% feed-grade Vitamin C + 850g of glucose + 50g of 0.3% hypericin extract) at a rate of 500g per acre by sprinkling it over the feeding area.

[0034] Furthermore, the entire fry rearing period is approximately 80-90 days. Due to the cannibalistic nature of sea bass fry, in the Baijiao area of ​​Zhuhai, fry are screened every 15-20 days. In low-salinity ponds, only one screening is arranged during the fry rearing period, generally around 35-40 days after stocking. Fry are usually screened according to two sizes, with larger fish assigned to Zone 1 and smaller fish retained in their original zone (Zone 2). Zone 3 remains the main area for water management. Sea bass are settled in ponds from 0.4g-0.8g to 30-100g. Due to the different sources of fry, the growth rate of different batches of fry during the fry rearing period will vary considerably.

[0035] Furthermore, fish health management employs water quality management and normal feeding management, closely linking water quality control with feeding to achieve a balance between healthy water and healthy fish. Regarding water quality management, except during the fry screening period, water disinfection and detoxification are generally not performed, and aerators operate 24 hours a day. The fishpond depth is adjusted via pipe settings; during rainfall, 10-20cm of bottom water is pumped out of the collection area. During high temperatures, no additional water is added; water is naturally evaporated and replaced by natural rainfall. Water management primarily focuses on algae cultivation and fertilization, mainly using lime granules to adjust transparency, zeolite powder and / or dolomite powder to adjust turbidity, and glucose, brown sugar, phosphate fertilizer, urea, and / or potassium fertilizer for fertilization, with very little use of microbial agents. Water regulation is achieved through water circulation in the main water control area, resulting in an overall water quality that is lively, fresh, clear, and transparent.

[0036] Furthermore, Zone 3 is designated as the main water control zone, equipped with a waterwheel aerator. Two water circulation zones are formed using the aerator and spaced perimeter netting. These zones are primarily used for water circulation and the main application of water-regulating products after seedling stocking, such as the fixed-point application of lime granules, with over 60% of the dosage applied in Zone 3 (see...). Figure 3 ).

[0037] Furthermore, throughout the entire fry stage, feed normally as much as possible, maintaining stable feeding during special weather conditions, gradually increasing feed, without reducing or stopping feeding. Strengthen anti-stress and health-preserving feeding by sprinkling the feed in the feeding area during feeding, without mixing it into the feed or administering it orally, and without using antibiotics. The core formula for health-preserving feeding is [100g of 98% feed-grade Vitamin C + 850g of glucose + 50g of 0.3% hypericin extract], and formula 2 is [100g of 98% feed-grade Vitamin C + 820g of glucose + 80g of hawthorn (200 mesh ultrafine powder)]. Use them separately, preferably freshly prepared and used immediately. For the first application of health-preserving feed, use formula 1, generally at a dosage of 500g per acre of water surface before the first feeding after fry stocking; formula 2 is generally used after fry screening or after special weather conditions, at a dosage of 500g per acre of water surface; the interval between health-preserving treatments for the fish population should be ≥20 days, and the number of treatments is generally 2-3 times.

[0038] Furthermore, sampling should be conducted every 7-10 days. Sampling can be carried out at the same time as afternoon feeding. 10-30 fish can be sampled, and the total weight is weighed. Then, divide by the number of fish to obtain the average weight. In the early stage (e.g., the first 10 days), the total number is calculated based on 85% of the number of fish to obtain the total weight. At the same time, the initial daily feeding amount is determined based on the total weight, and then adjusted according to the actual feeding situation. At the beginning of training, it is advisable to feed slowly and master the rhythm. Then feed at a slow-fast-slow rhythm, with the benchmark being that most fish leave and stop eating.

[0039] Regular sea bass fry feed can be used for normal feeding, and the specific feeding amount can be determined according to the table below.

[0040] Basic feeding table for sea bass fry

[0041] Sampling specification Product specification Daily feeding rate (percentage of body weight) Feeding frequency (times / day) ≦0.5g Powder 10-12％ 2 0.5-2.5g Powder + granules or broken pieces 8-10％ 2 2.5-5.0g 0 granules (0.5 mm) 6-8％ 2 5.0-10g 1 granules (1.2 mm) 4-6％ 2 10-15g 2 granules (2.0 mm) 3.0-4.5％ 2 15-50g 3 granules (3.0 mm) 2.5-3.0％ 2 50-100g 4 granules (4.0 mm) 2.0-2.5％ 2

[0042] Example 1

[0043] In February 2023, seedling preparation work was carried out at the Taiwan-funded Aquatic Seedling Breeding Base in Pingsha Town, Jinwan District, Zhuhai City, Guangdong Province. On March 2, 38,000 seedlings were stocked for fry rearing. The seedlings came from Fujian and had an average weight of 0.4g-0.6g. By May 16, samples were taken and the seedlings met the standard for pond establishment. The overall survival rate exceeded 50%, with an average weight of 32.5g and an average length of 16.5cm, slightly exceeding the average level of seedlings in the dominant area of ​​Baijiao, Zhuhai at that time (the median survival rate of seedlings to pond establishment in this area over the past 5 years is generally 50%, which is the industry standard).

[0044] Pond conditions: The pond is a newly opened open pond with an area of ​​3.1 acres. It is oriented east-west and divided into three sections from east to west: left, middle and right. These sections are the seedling screening and diversion area (section 1), the main seedling feeding area (section 2), and the water regulation and control area (section 3).

[0045] In February 2023, the original bottom water in the pond was drained, and water was introduced to a depth of 2.0m using 80-mesh granules. 10kg of bleaching powder and 30g / mu of 10% Sophora flavescens extract were used for disinfection and pest control at a depth of [insert depth here]. Five days later, 2kg / mu of biological bottom cleaner (granular, containing 3 billion Bacillus subtilis per gram) was evenly spread throughout the pond at a depth of [insert depth here] to improve the bottom. Five days later, 20kg of lime granules were evenly spread throughout the pond to adjust the water transparency to approximately 60cm. Three days later, an organic acid product was used for detoxification. The water conditioning was completed, and the pond was ready for seedling introduction.

[0046] The main water quality indicators before seedling introduction are as follows:

[0047] Index ph value Ammonia nitrogen Nitrite Dissolved oxygen (open aeration machine) Salinity Total alkalinity Total hardness Value 8.2 0 0.05 8.0 6.8 ppt 130 ppm 1000 ppm

[0048] For the trial fry test, take 10 fish fry, put them in a test fry bag, and place them in water at a depth of 50cm for 24 hours. After 24 hours, observe the survival rate of the fry. If all of them survive and the survival rate is ≥90%, then the batch of fry can be purchased from that location.

[0049] Furthermore, 24 hours before the arrival time of the fish fry, drain 20cm of bottom water, and disinfect 12-16 hours later using 300ml / mu / meter water depth of 10% povidone-iodine. 0.5 hours before the fry are introduced, spray the entire pond with 50g / mu / meter water depth of 98% feed-grade vitamin C + 450g / mu / meter water depth of 98% feed-grade vitamin C.

[0050] The fish fry, sourced from Fujian, were transported together with fry from Baijiao to Baijiao before being distributed to Pingsha, Jinwan District, Zhuhai. Upon arrival before 8:00 AM on March 2nd, the fry underwent a rapid count and inspection. The fry were 3cm in length and weighed 0.4g-0.6g, totaling over 38,000 fry, weighing 20kg. Samples were retained for virus testing. The fry were then gently released into the intermediate partitioned pond (zone 2), where they quickly dispersed and entered the water, indicating good fry quality.

[0051] Initial pond management and feeding: On the second day, the pond was inspected and fed. Ten fry were lost, but there were no instances of them swimming or burying themselves near the edge. The initial feeding amount was 0.5 kg / ton, using fry feed, twice a day. 0.5 hours before the first feeding, in Zone 2, a mixture of Formula 1 [100g of 98% feed-grade Vitamin C + 850g of glucose + 50g of 0.3% hypericin extract] was applied at a rate of 500g / mu.

[0052] Fish health management mainly involves water quality management. During the stocking period, the water quality management requirements are dissolved oxygen at a depth of 1m above 7.6, ammonia nitrogen is basically zero, the pH value is not higher than 8.5 throughout the day, and nitrite is ≤0.1. Special attention should be paid to changes in dissolved oxygen and ammonia nitrogen levels.

[0053] Severe weather management: During the seedling stage from February to May, the severe weather encountered in the early stages mainly included strong convection, heavy rain, continuous overcast and rainy weather, thunderstorms, and strong winds. Insufficient sunlight, unstable water temperature, and water levels in the pond easily rising by 25-35cm were common. In mid-to-late March, the pond underwent comprehensive water conditioning using lime granules and adopted a natural feeding method, which largely withstood the impact of severe weather. For example, on April 4th, 15 catties of lime granules were added at fixed points, and on April 5th, one bag of zeolite powder and 6 catties of glucose were added at fixed points, with ideal results, maintaining water stability during the subsequent long period of overcast and rainy weather. The later period involved heavy rain and high temperatures. For example, from May 29th to 31st, 2023, the daily air temperature reached 33℃, the surface water temperature of the pond was 36℃, and the temperature at a depth of 50cm was 45℃. At the beginning of the high-temperature weather, 50g of 98% feed-grade vitamin C and 450g of glucose per mu (approximately 0.067 hectares) were sprinkled throughout the pond in the morning or evening at a water depth of 1 meter. Feeding was maintained steadily, and normal feeding was only resumed after at least 7 days of sustained high temperatures. Attention was paid to water evaporation, and the water depth was maintained at least 1.5m. After 3 days of high temperatures, zeolite powder was first sprinkled along the direction of water flow, followed by a small amount of potassium fertilizer at a rate of 500g per mu (approximately 0.067 hectares), applied intermittently as needed, with 60% of the amount applied to the main water control area.

[0054] Regarding the handling of abnormal situations, no diseases occurred throughout the entire fry rearing process. The main abnormal situation was that on March 9th, the fish stopped eating after being fed in the evening. The basic treatment was to immediately apply 50g of Vitamin C and 450g of glucose to the fry rearing area. The next day, oxygenation products and microbial products were used to improve the bottom, and the fish population quickly stabilized. However, due to the uncertainty of microbial products, water quality became unstable after their use, resulting in yellow and turbid water. The treatment was to apply 10kg of lime granules at specific locations on March 16th. The water quality stabilized after 3 days. The use of lime granules has strict conditions: generally, the pH value should not be higher than 8.4 in the afternoon, there should be no ammonia nitrogen, and the dissolved oxygen should be higher than 7.5. It is mainly applied before and after the waterwheel aerator in the water conditioning area of ​​Zone 3 and in the return water area. In the main rearing area of ​​Zone 2, it is applied opposite the feeding area, utilizing water flow for diffusion.

[0055] Sampling of fry: Samples were taken from the fry to check their appearance, body surface, and growth rate. On April 7th, samples were taken during afternoon feeding. The sample size was 30 fish at random, with an average weight of 6g and an average length of 7.2cm; the fish were in good health.

[0056] The initial screening of the fry was carried out on April 13th. The fry were sorted using a 10-sided sieve and divided into two specifications: 10 facing up and 10 facing down.

[0057]

[0058] The fry were sampled again and settled in the pond. On May 16, the fry were sampled to check their appearance, body surface and growth rate. Samples were taken in the afternoon when feeding, with a sample size of 30 fish, with an average weight of 32.5g and an average length of 16.5cm; the fish were in good health.

[0059] Fish health management mainly includes basic water conditioning, feeding management, and health management. Basic water conditioning primarily aims to significantly enhance the water body's self-repair and ecological capabilities. Disinfectants are not used except before and after fry screening, and no detoxification is performed before or after rain. Lime granules are used flexibly in conjunction with water flow in the main water conditioning control area for water quality regulation. Targeted fertilization is combined with feeding based on the water's salinity, total alkalinity, and total hardness characteristics. Feeding is based on the fish's weight, selecting the feed type and amount, and gradually increasing the feed. For health management, no internal treatment is given. Formula 1 [98% feed-grade Vitamin C 100g + glucose 850g + 0.3% hypericin extract 50g] and Formula 2 [98% feed-grade Vitamin C 100g + glucose 820g + 80g hawthorn (200 mesh ultrafine powder)] are sprinkled in the feeding area. Formula 2 is generally used after fry screening or in special weather conditions.

[0060] Compared to traditional sea bass farming practices in Baijiao, Zhuhai, this invention reduces the number of fry screenings, the use of disinfectants, and pond detoxifiers. No additional water is added except for natural rainfall. Feeding is maintained at a generally normal rate, without significant cessation due to inclement weather. Lime granules are used to adjust transparency, zeolite powder and / or dolomite powder to adjust turbidity, and glucose and brown sugar are used as fertilizers, depending on feeding and weather conditions. The fish population is of good quality, with uniform scales, smooth surfaces, normal body color, and high vitality. The number of fish successfully screened and scraped is 0.568, the total number of fish successfully placed in the pond exceeds 0.52, and the average weight at the pond is 32.5g, reaching the upper-middle level for sea bass farmers in Baijiao, Zhuhai at that time.

[0061] Example 2

[0062] The pond has an area of ​​1.6 acres and is equipped with one impeller-type aerator. Water is filtered once using an 80-mesh filter to a depth of 2.5 meters. The water quality indicators after water intake are as follows:

[0063]

[0064] Water conditioning: Use 10kg of bleaching powder + 30g of 10% Sophora flavescens extract per mu (approximately 0.067 hectares) for disinfection and pest control at a water depth of 1 meter. After 7 days, use EM bacteria for regulation. After 3 days, use organic acid for detoxification. After 3 days, use lime granules to adjust the water transparency to 60cm-70cm. The measured water indicators are: pH 8.2, ammonia nitrogen 0, nitrite 0.10, dissolved oxygen 8, salinity 6.9ppt, water temperature 23℃, total alkalinity 100ppm, hardness 1000ppm, and transparency 60cm-80cm. The overall water quality is kept lively, refreshing, and clear. During the water conditioning period, the aerator is run continuously for 24 hours. It takes 13-15 days from the completion of water intake to the completion of water quality regulation.

[0065] Stocking: 16,000 fry were stocked on March 10th, with an average weight of 0.6-0.8g. The parent fish were large and were wild-caught. After initial sizing in Zhuhai, the fry arrived at the site in 2 hours.

[0066] Water quality management during the nursery stage primarily involves avoiding or minimizing the use of disinfectants and antidotes. No additional water is introduced except for natural rainfall. Feeding is maintained at a generally normal rate, without significant cessation due to inclement weather. Based on feeding levels and weather conditions, lime granules are used to adjust transparency, zeolite powder and / or dolomite powder to adjust turbidity, and glucose, brown sugar, phosphate fertilizer, urea, and / or potassium fertilizer are applied to fertilize the water. Dissolved oxygen at a depth of 1 meter is maintained above 7.5 ppm. Throughout the nursery stage, there is no ammonia nitrogen, nitrite is ≤0.1 ppm, and pH does not exceed 8.5.

[0067] The health care feeding mainly uses Formula 1 [100g of 98% feed-grade vitamin C + 850g of glucose + 50g of 0.3% hypericin extract] and Formula 2 [100g of 98% feed-grade vitamin C + 820g of glucose + 80g of hawthorn (200 mesh ultrafine powder)]. The usage method can be referred to the above instructions and will not be repeated here.

[0068] Sampling of fry: Samples were taken from the fry to check their appearance, body surface, and growth rate. On April 7th, samples were taken during afternoon feeding. The sample size was 30 fish at random, with an average weight of 10g and an average length of 9.5cm; the fish were in good health.

[0069] Seedling screening

[0070]

[0071] Second sampling results and pond stabilization results

[0072] The fry were sampled again and placed in ponds. On May 16, the fry were sampled to check their appearance, body surface, and growth rate. The sample size was 30 fish at random, with an average weight of 62.5g and an average length of 21.5cm. The fish were in good health, and more than 50% of them were placed in ponds.

[0073] Tracking the performance of this batch of parent fish fry in the Baijiao aquaculture area, the proportion of fry raised in the large pond has exceeded 50%, and the growth rate is much faster than that of fry transported over long distances. In comparison, the growth rate of Pingsha is slightly better.

[0074] The above description is merely an embodiment of the present invention and is not intended to limit the scope of patent protection of the present invention. Any use of the contents of the present invention specification and drawings for the germination of sea bass fry in low salinity ponds is similarly included within the scope of patent protection of the present invention.

Claims

1. A method for raising sea bass fry in low-salinity ponds, comprising: The pond is cleaned by removing debris and draining the bottom water. Then, filtered water is introduced to a depth of 1.8m-2.0m. During the entire process, no additional water is introduced except for natural rainfall. When selecting a pond area of ​​3-5 mu, divide the pond into 3 zones: the main stocking zone, the seedling distribution zone, and the main water control zone. The main water control zone is located downwind, and the main stocking zone is located between the seedling distribution zone and the main water control zone. Each zone is separated by a perimeter net. Paddlewheel aerators are installed in the seedling distribution zone and the main stocking zone, while a paddlewheel aerator is installed in the main water control zone to achieve water circulation. A bottom collection area is also set up in the main water control zone to pump out bottom water. 60% of the water control inputs are placed in the main water control zone, and the remainder are placed in the seedling distribution zone and the main stocking zone. The water control inputs are generally placed in an L-shaped or U-shaped open manner, without forming a closed loop or being placed throughout the entire pond. Before stocking, the pond water quality should be pre-treated: First, use 10 kg / mu / meter water depth of bleaching powder and 30 g / mu / meter water depth of 10% Sophora flavescens extract for disinfection and pest control; 5-7 days later, use EM bacteria or granular Bacillus products to improve the bottom; 3-5 days after bottom improvement, detoxify the water; the pH of the treated water should be between 7.8 and 8.3, ammonia nitrogen should be 0, nitrite should be ≤0.10, dissolved oxygen at a depth of 1m with the aerator running at full capacity should be ≥7.5, salinity should be ≤7ppt, water temperature should be ≥15℃, total alkalinity should be 120-150ppm, hardness should be 800-1000ppm, and transparency should be 50-80cm. 24-48 hours before the arrival time of the fish fry, remove 20cm of the bottom water from the water body that has undergone preliminary conditioning treatment. 12-16 hours later, disinfect the water body. 0.5 hours before the fry are introduced, apply 50g of 98% feed-grade vitamin C + 450g of glucose per mu (meter of water depth) to the entire pond. After stocking, fish health is maintained by sprinkling the solution in the feeding area. No feed or oral administration of antibiotics is used. The sprinkling formulas are as follows: Formula 1 consists of 100g of 98% feed-grade Vitamin C + 850g of glucose + 50g of 0.3% hypericin extract; Formula 2 consists of 100g of 98% feed-grade Vitamin C + 820g of glucose + 80g of 200-mesh ultrafine hawthorn powder. Formulas 1 and 2 are used separately. Formula 1 should be used for the first sprinkling, and the interval between fish health maintenance treatments should be ≥20 days. Formula 1 should be used before the first feeding after stocking, and Formula 2 should be used after fry screening or in special weather conditions. Both Formulas 1 and 2 should be prepared and used immediately at a dosage of 500g / acre. During the seedling stage, no water disinfection or detoxification treatment is carried out except for seed screening. The aerator is run continuously for 24 hours. During rainfall, 10-20cm of bottom water is pumped out. During high temperatures, no additional water is added. Water is replaced by natural evaporation and natural rainfall. Water management is mainly based on algae cultivation and fertilization. Lime particles are used to adjust transparency, zeolite powder and / or dolomite powder are used to adjust turbidity, and glucose, brown sugar, phosphate fertilizer, urea and / or potassium fertilizer are used to fertilize the water. Feed normally throughout the seedling stage. Maintain stable feeding during special weather conditions, gradually increase feed, do not reduce feed, and do not stop feeding. Only one screening is arranged during the fry rearing period. The screening is carried out 35-40 days after the initial stocking. After screening, the larger fish are transferred to the screening and distribution area, while the smaller fish are kept in the main stocking area.

2. The method for raising sea bass fry in low-salinity ponds according to claim 1, characterized in that: During the coagulation period, ensure that dissolved oxygen ≥ 7.5, no ammonia nitrogen, nitrite ≤ 0.1, and pH value not exceeding 8.5 at a water depth of 1m with the aerator fully running.

3. The method for raising sea bass fry in low-salinity ponds according to claim 1, characterized in that: The stocking density in the seedling area should be controlled at ≤40,000 fish / acre.

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