An environmental enrichment device and method for enrichment culture of juvenile Scorpionfish.

Abstract

This invention discloses an environmental enrichment device for enrichment culture of juvenile scorpionfish, characterized in that: the device includes a first box (1), the four side walls of the first box (1) are respectively connected to a transparent tube (2), the bottom end of the transparent tube (2) is connected to the top plate of a second box (3), the bottom end surfaces of the four second boxes (3) are coplanar, and a camera (4) is provided on the bottom surface of the first box (1), a plurality of feeding holes (5) are provided on the side wall of the transparent tube (2), a flap (6) matching the feeding hole (5) is hinged in the transparent tube (2), and the outline of the flap (6) is larger than the aperture of the feeding hole (5), the feeding hole (5) is located on the lower side of the transparent tube (2), and a screen (7) is provided at the connection between the transparent tube (2) and the second box (3).

Description

Technical Field

[0001] This invention relates to the field of marine fish aquaculture research, and in particular to an environmental enrichment device for enrichment culture of juvenile Scorpionfish, and a method for environmental enrichment acclimatization using the device. Background Technology

[0002] In the artificial rearing of juvenile Scorpionfish, to improve the rearing effect, breeders hope that the rearing environment and conditions can be as similar as possible to the food habitat in natural waters, thereby enhancing the rearing effect of juvenile fish. Therefore, in the traditional rearing process, live food is put into the rearing container according to the above principle. However, when live food is fed directly, the live food is concentrated and eaten by the juvenile fish. The remaining live food is affected by the fish school and cannot form a multi-layered random distribution in the water as in the marine environment. Therefore, it is impossible to achieve the purpose of simulating the feeding of juvenile fish in the wild. At the same time, in the process of juvenile fish fighting for live food, they may bite each other's bodies and gills, which can cause injury or even death to the juvenile fish.

[0003] Therefore, a method or apparatus is needed to solve the above problems. Summary of the Invention

[0004] This invention addresses the aforementioned shortcomings of existing technologies by proposing a simple, ingeniously designed, and rationally laid-out environmental enrichment device. It also discloses a method for acclimatizing juvenile Scorpionfish using this device, thereby reducing their aggressive behavior and alleviating stress in the aquaculture environment. This method can significantly improve brain cell proliferation and neural transfer levels, thus enhancing the fish welfare of juvenile Scorpionfish and improving the quality of Scorpionfish aquaculture.

[0005] The technical solution of this invention is: an environmental enrichment device for the enrichment and culture of juvenile Scorpionfish, characterized in that: the device includes a first box 1, the four side walls of the first box 1 are respectively connected to transparent tubes 2, the bottom end of the transparent tubes 2 is connected to the top plate of a second box 3, the bottom end surfaces of the four second boxes 3 are coplanar, and a camera 4 is provided on the bottom surface of the first box 1.

[0006] The transparent tube 2 has multiple feeding holes 5 evenly spaced on its side wall. A flap 6, matching the feeding holes 5, is hinged inside the transparent tube 2, and the outline of the flap 6 is larger than the diameter of the feeding holes 5. The feeding holes 5 are located on the lower side of the transparent tube 2. A screen 7 is provided at the connection between the transparent tube 2 and the second housing 3.

[0007] The second housing 3 has multiple avoidance holes 8 on its side wall.

[0008] The device is placed in the aquaculture container 9 and is equipped with a water circulation system. The outlet of the water inlet pipe 10 in the water circulation system is connected to the first housing 1.

[0009] The diameter of the feeding hole 5 ranges from 0.3 to 0.4 cm, and the diameter of the avoidance hole 8 ranges from 3 to 4 cm.

[0010] The screen 7 is rotatably connected to the transparent tube 2 via a rotating shaft. A stop 11 matching the screen 7 is provided at the end of the transparent tube 2. Under the action of the stop 11, the screen 7 can only swing in the direction of the inside of the transparent tube 2, and the width of the gap that the screen 7 can open is 0.3-0.4cm.

[0011] The four second boxes 3 are distributed at the four corners of the aquaculture container 9.

[0012] A method for enriching and culturing juvenile Scorpionfish using the apparatus described above, characterized in that the method is carried out according to the following steps:

[0013] A. Inject filtered seawater into aquaculture container 9, continuously aerate using air stones, suck the bottom once a day, and change the water once a day, with a daily water change volume of 50%.

[0014] B. Construct experimental group culture container 9 and control group culture container 9 according to step A. The experimental group is divided into experimental group 1 and experimental group 2, and the control group is divided into control group 1 and control group 2. Juvenile Scorpionfish with a body length of 2.45±0.55cm are released into the culture containers 9. Ten fish are released into each of experimental group 1 and control group 1, and six fish are released into each of experimental group 2 and control group 2.

[0015] C. At 8:00 AM and 2:00 PM daily, sedimented pellet feed was fed to control group 1 and control group 2, respectively. The average diameter of the sedimented pellet feed was 2 mm. The feeding status of the juvenile Scorpionfish was observed during the feeding process, and feeding was stopped when they showed signs of satiation. Starting at 8:00 AM daily, live food was fed to experimental groups 1 and 2. The live food was Litopenaeus vannamei (whiteleg shrimp) with a body length of 10.1 ± 0.3 mm. Feeding was carried out through the first tank 1, and 8 Litopenaeus vannamei were fed into each transparent tube 2. Experimental groups 1 and 2 were checked every three hours, and the number of surviving Litopenaeus vannamei in each transparent tube 2 was checked. If the number was less than 8, it was increased to 8. The acclimatization period was 56 days.

[0016] D. Clean the enrichment device every 7 days.

[0017] E. After the first feeding each day, use camera 4 to film the aggressive behavior of juvenile Scorpionfish in the experimental and control groups during feeding for 30 minutes. At 16:30 each day, use camera 4 to film the aggressive behavior of juvenile Scorpionfish in the experimental and control groups in a non-feeding state for 30 minutes.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] When raising juvenile Scorpionfish using traditional methods, live food is often directly fed into the rearing container. However, this method results in uneaten food being too scattered in the water, requiring frequent cleaning. This cleaning process can negatively impact the acclimatization of the juveniles, and the loss of uneaten food can lead to water quality deterioration. Direct feeding of live food also results in the juveniles crowding and consuming the food, leaving the remaining live shrimp to be affected by the fish population. This prevents the fish from achieving a multi-layered, random distribution in the water, failing to simulate the feeding characteristics of wild juveniles in the marine environment. Furthermore, competition and biting can lead to injuries and even death of the fish.

[0020] The environmental enrichment device and method disclosed in this invention for the social enrichment culture of juvenile Scorpionfish using this device simulate the feeding habitat of Scorpionfish based on its feeding characteristics, and the size of its population reflects natural changes observed in the wild, thus providing a living environment similar to that of wild populations for early rearing. This method not only reduces the impact of stress factors on juvenile Scorpionfish during rearing, but also tames the larvae, reduces their aggressive behavior, alleviates stress in the rearing environment, and improves brain cell proliferation and neural transfer, thereby improving fish welfare and the quality of Scorpionfish rearing. It is low-cost, easy to operate, and can be widely applied to large-scale aquaculture, showing promising application prospects. Attached Figure Description

[0021] Figure 1 This is a top view of an embodiment of the present invention.

[0022] Figure 2 yes Figure 1 Sectional view along direction AA.

[0023] Figure 3 yes Figure 2 Enlarged view of part B in the image.

[0024] Figure 4 yes Figure 2 Enlarged view of section C in the image. Detailed Implementation

[0025] Specific embodiments of the present invention will now be described in conjunction with the accompanying drawings. Figures 1 to 4The image shows an environmental enrichment device for the enrichment and culture of juvenile Scorpionfish (Scorpionfish schlegelii). The device includes a first box 1, whose four side walls are connected to transparent tubes 2. The bottom ends of the transparent tubes 2 are connected to the top plate of a second box 3. The bottom surfaces of the four second boxes 3 are coplanar. A camera 4 is mounted on the bottom surface of the first box 1.

[0026] The transparent tube 2 has multiple feeding holes 5 evenly spaced on its side wall. A flap 6, matching the feeding holes 5, is hinged inside the transparent tube 2, and the outline of the flap 6 is larger than the diameter of the feeding holes 5. The feeding holes 5 are located on the lower side of the transparent tube 2. A screen 7 is provided at the connection between the transparent tube 2 and the second housing 3.

[0027] The second housing 3 has multiple avoidance holes 8 on its side wall.

[0028] The device is placed in the breeding container 9 and is equipped with a water circulation system. The outlet of the water inlet pipe 10 in the water circulation system is connected to the first box 1.

[0029] The four second boxes 3 are distributed at the four corners of the aquaculture container 9.

[0030] The feeding hole 5 has a diameter range of 0.3-0.4 cm, and the avoidance hole 8 has a diameter range of 3-4 cm.

[0031] The screen 7 is rotatably connected to the transparent tube 2 via a rotating shaft. A stop 11 matching the screen 7 is provided at the end of the transparent tube 2. Under the action of the stop 11, the screen 7 can only swing in the direction of the inside of the transparent tube 2, and the width of the gap that the screen 7 can open is 0.3-0.4cm.

[0032] When using the above-mentioned environmental enrichment device for the enrichment and culture of juvenile Scorpionfish, follow these steps:

[0033] First, filter seawater is injected into aquaculture container 9. Aeration is continuously achieved using air stones, with the bottom sucked in once daily and the water changed once daily, replacing 50% of the water daily.

[0034] The experimental group and control group were constructed using the above method. The experimental group was divided into experimental group 1 and experimental group 2, and the control group was divided into control group 1 and control group 2. Juvenile Scorpionfish with a body length of 2.45±0.55cm were released into the above-mentioned culture containers 9. Ten fish were released into each of experimental group 1 and control group 1, and six fish were released into each of experimental group 2 and control group 2.

[0035] At 8:00 AM and 2:00 PM daily, sedimented pellet feed with an average diameter of 2 mm was fed to control groups 1 and 2, respectively. The feeding status of the juvenile *Scorpionichthys schlegelii* was observed during feeding, and feeding was stopped once the fish showed signs of satiation. Starting at 8:00 AM daily, live food (*Litopenaeus vannamei*) with a body length of 10.1 ± 0.3 mm was fed to experimental groups 1 and 2 through the first tank 1, with 8 *Litopenaeus vannamei* shrimp placed in each transparent tube 2. Experimental groups 1 and 2 were checked every three hours, and the number of surviving *Litopenaeus vannamei* shrimp in each transparent tube 2 was also checked. If the number was less than 8, the number was increased to 8. The acclimatization period was 56 days.

[0036] Since all feeding holes 5 are located on the lower side of the transparent tube 2, the flap 6 will automatically snap into place on the inside of the feeding hole 5 under the action of gravity, thus sealing it. At the same time, since the flipping direction of the flap 6 is opposite to the direction of water flow, the flap 6 will also press tightly against the feeding hole 5 under the action of water pressure, thus sealing it. When feeding is performed on the experimental group, since all the live bait enters the transparent tube 2, the juvenile Scorpionfish will try to enter the transparent tube 2 under the attraction of the live bait. They will push open the flap 6, but since the size of the feeding hole 5 is relatively small (0.3-0.4cm), it can only accommodate the mouth of the juvenile Scorpionfish. Therefore, the juvenile Scorpionfish will insert their mouths into the transparent tube 2 and catch the swimming live bait. When the juvenile Scorpionfish is not feeding, the flap 6 will automatically close.

[0037] Similarly, the juvenile scorpionfish that enter the second tank 3 through the avoidance hole 8 will also push open the screen 7 driven by their feeding instinct. However, due to the limited opening angle of the screen 7, the juvenile scorpionfish can only probe into the transparent tube 2 with their mouths and catch swimming live prey. When the juvenile scorpionfish is not feeding, the screen 7 will automatically close under the action of water pressure.

[0038] During the aforementioned acclimatization process, the enrichment equipment was cleaned every 7 days.

[0039] After the first feeding each day, camera 4 was used to film the aggressive behavior of juvenile Scorpionfish in both the experimental and control groups during feeding, with a filming time of 30 minutes. At 4:30 PM each day, camera 4 was also used to film the aggressive behavior of juvenile Scorpionfish in both the experimental and control groups when they were not feeding, with a filming time of 30 minutes.

[0040] Analysis of the captured video footage leads to the following conclusions:

[0041] The frequency of aggressive behavior among juvenile Scorpionfish fed live bait (including experimental group 1 and experimental group 2) was significantly lower than that in the control group fed sedimented pellet bait (including control group 1 and control group 2). Furthermore, even among experimental groups, the frequency of aggressive behavior among juvenile Scorpionfish in experimental group 1 (with a population of 10) was significantly lower than that in experimental group 2 (with a population of 6).

[0042] In other words, behavioral observations show that the aggressive behavior of juvenile Scorpionfish populations reduced and the environmental stress they experienced decreased after environmental enrichment treatment and domestication.

[0043] After the domestication process was completed, live bait, consisting of shrimp and algae, was introduced into the control groups (including control group 1 and control group 2) that had not undergone environmental enrichment domestication. Observations revealed that the juvenile Scorpionfish in the control group exhibited relatively fewer predation attempts and escape behaviors when fed shrimp bait; when fed algae bait, they engaged in aggressive behaviors to compete for food; and the control group also exhibited multiple intraspecific aggression behaviors under non-feeding conditions.

[0044] Live bait, consisting of shrimp and shellfish, was introduced into the experimental groups (including experimental group 1 and experimental group 2) that had undergone environmental enrichment and domestication. Observations showed that after the live bait was introduced into the transparent tube 2, the juvenile scorpionfish would rush towards the live bait and actively push open the flap 6 and the screen 7 to feed. However, the number of times they attacked each other was relatively small. At the same time, the number of intraspecific aggression behaviors in the experimental groups was also relatively small under non-feeding conditions.

[0045] In other words, behavioral observations showed that the predation behavior of juvenile Scorpionfish populations that underwent environmental enrichment treatment and domestication was significantly enhanced, and the intraspecific aggression during feeding due to competition for food, as well as intraspecific aggression during non-feeding periods, was reduced compared to the control group.

[0046] After environmental enrichment and domestication, three juvenile Scorpionfish from each of the experimental and control groups, totaling 12 juvenile Scorpionfish, were collected for cortisol, MDA concentration, and CAT, GSH-Px, SOD activity and gene expression assays. The results showed that:

[0047] Compared with the control group, the experimental group showed significantly reduced CAT activity (16.34%), GSH-Px activity (50.12%), and SOD activity (12.55%). At the same time, the frequency of aggressive behavior during feeding (62.91%) and the frequency of aggressive behavior during idle time (53.51%) were both reduced. Furthermore, the experimental group showed increased coefficient of variation in body weight (28.06%), and increased expression of brain pcna (182.75%), dcx (86.7%), and neurod (154.19%) genes.

[0048] Compared with experimental group 2 (small-scale population), experimental group 1 (large-scale population) significantly reduced MDA content (27.4%), while the frequency of aggressive behavior during feeding (31.91%) and during idle time (32.09%) was also reduced. Furthermore, it enhanced basal cortisol levels (11.11%), dcx (78.34%), and neurod (72.54%) gene expression; and increased CAT activity (52.56%), GSH-Px activity (57.78%), and SOD activity (51.73%).

[0049] The above results indicate that domestication using this environmental enrichment device can not only reduce the stress factors affecting juvenile Scorpionfish during rearing, but also reduce their aggressive behavior, eliminate stress in the aquaculture environment, and improve brain cell proliferation and neural transfer levels, thereby improving the fish welfare of juvenile Scorpionfish, enhancing the quality of Scorpionfish rearing, and also improving the adaptability of juveniles for stock enhancement and release.

Claims

1. An environmental enrichment device for the enrichment and culture of juvenile Scorpionfish, characterized in that: The device includes a first box (1), the four side walls of the first box (1) are respectively connected to a transparent tube (2), the bottom end of the transparent tube (2) is connected to the top plate of the second box (3), the bottom end surfaces of the four second boxes (3) are coplanar, and a camera (4) is provided on the bottom surface of the first box (1). The transparent tube (2) has multiple feeding holes (5) evenly spaced on its side wall. Inside the transparent tube (2), there is a flap (6) that matches the feeding holes (5). The outline of the flap (6) is larger than the diameter of the feeding holes (5). The feeding holes (5) are located on the lower side of the transparent tube (2). A screen (7) is provided at the connection between the transparent tube (2) and the second box (3). The second box (3) has multiple hiding holes (8) on its side wall. The device is placed in the aquaculture container (9) and is equipped with a water circulation system. The outlet of the water inlet pipe (10) in the water circulation system is connected to the first box (1). The diameter of the feeding hole (5) ranges from 0.3 to 0.4 cm, and the diameter of the hiding hole (8) ranges from 3 to 4 cm. The screen (7) is rotatably connected to the transparent tube (2) via a rotating shaft. A stop (11) matching the screen (7) is provided at the end of the transparent tube (2). Under the action of the stop (11), the screen (7) can only swing towards the inside of the transparent tube (2), and the width of the gap that the screen (7) can open is 0.3-0.4cm.

2. The environmental enrichment device for enrichment aquaculture of juvenile Scorpionfish as described in claim 1, characterized in that: The four second boxes (3) are distributed at the four corners of the aquaculture container (9).

3. A method for enriching and culturing juvenile Scorpionfish using the apparatus as described in claim 1, characterized in that: The method is performed according to the following steps: A. Inject filtered seawater into the aquaculture container (9), continuously aerate using air stones, suck the bottom once a day, change the water once a day, and change 50% of the water daily. B. Construct the experimental group culture container (9) and the control group culture container (9) according to step A. The experimental group is divided into experimental group one and experimental group two, and the control group is divided into control group one and control group two. Juvenile Scorpionfish with a body length of 2.45±0.55cm are put into the culture containers (9). Ten fish are put into experimental group one and control group one, and six fish are put into experimental group two and control group two. C. At 8:00 AM and 2:00 PM daily, sedimented pellet feed was fed to control group 1 and control group 2 respectively, with an average diameter of 2 mm. The feeding status of the juvenile scorpionfish was observed during the feeding process, and feeding was stopped when they showed signs of satiation. Starting at 8:00 AM daily, live bait was fed to experimental group 1 and experimental group 2. The live bait was whiteleg shrimp with a body length of 10.1 ± 0.3 mm. Feeding was carried out through the first box (1), and 8 whiteleg shrimp were fed in each transparent tube (2). Experimental group 1 and experimental group 2 were checked every three hours, and the number of whiteleg shrimp surviving in each transparent tube (2) was checked. If the number was less than 8, it was supplemented to 8. The acclimatization period was 56 days. D. Clean the enrichment device every 7 days. E. After the first feeding each day, use camera (4) to film the aggressive behavior of juvenile scorpionfish in the experimental group and the control group during the feeding process for 30 minutes. At 16:30 each day, use camera (4) to film the aggressive behavior of juvenile scorpionfish in the experimental group and the control group in the non-feeding state for 30 minutes.

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