Method for improving body color and growth of red drum juvenile fish

Abstract

The application relates to a method for improving the body color and growth of red drum juvenile fish, which comprises the following steps: placing red drum juvenile fish in indoor culture barrels for culture, feeding the fish with feed, feeding the fish once in the morning and once in the afternoon every day, and cleaning the water and the bottom of the culture barrels every day; the culture conditions are as follows: i) the culture barrels are continuously aerated by using nano gas stones, and the dissolved oxygen concentration is 6.5-7.4 mg / L; ii) the pH of the water in the culture barrels is 7.5-8.4; iii) the water temperature and salinity in the culture barrels remain relatively unchanged, and are 27.3-33.2 DEG C and 25-31 ‰ respectively; iv) the culture barrels are covered with light-shielding cloth, the light source for culture is blue light, and the light intensity from the edge of the culture barrel to the center is 250-1500 lux; and v) the culture cycle is more than 45 days. According to the preference of red drum for light environment, the application creates a suitable light environment for red drum, which can not only improve the growth and survival rate of red drum, but also improve the brightness and redness value of the body color of red drum, so that red drum juvenile fish with fast growth, good appearance and high survival rate are obtained, and the economic benefits of culture enterprises are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aquaculture, and particularly relates to an artificial breeding method of redfin snapper. BACKGROUND

[0002] Light is one of the important environmental factors affecting the growth and development of aquatic organisms. The feeding, growth, development and survival of fish are directly or indirectly affected by light. The current traditional method of directly using natural light cannot meet the needs of future intensive factory farming mode, and the research on efficient light conditions for increasing yield and quality needs to be strengthened.

[0003] Redfin snapper (Lutjanus erythopterus) belongs to the class of Osteichthyes, the subclass of Actinopterygii, the order of Perciformes, the family of Lutjanidae and the genus of Lutjanus. It inhabits widely in reef-sand mixed areas, gravel areas, rock areas, sandy areas or independent reefs in the open sea. However, the survival rate of redfin snapper is low in the actual breeding and seedling process. There are few reports on the light quality preference color of redfin snapper in the growth process. CN117941644A discloses a transportation device and method for improving the survival rate of redfin snapper fry, which discloses that the transportation condition of white light at 100 lux light intensity can improve the survival rate. SUMMARY

[0004] The present inventors have conducted extensive screening and research on various light quality conditions, and finally obtained a method for improving the body color and growth of redfin snapper fry, which comprises the following steps:

[0005] The redfin snapper fry is placed in an indoor breeding barrel for breeding, and feed is used for feeding during the period, and each feeding is performed once in the morning and once in the afternoon every day, and water changing and bottom cleaning are performed every day, and the breeding conditions are as follows:

[0006] i) nano air stone is used for continuous aeration in the breeding barrel, and the dissolved oxygen concentration is 6.5-7.4 mg / L,

[0007] ii) the pH of the water in the breeding barrel is 7.5-8.4,

[0008] iii) the water temperature and salinity in the breeding barrel remain relatively unchanged, and are 25-31℃ and 27.3-33.2‰, respectively,

[0009] iv) the breeding barrel is covered with a light-shielding cloth, the light conditions for breeding are set as blue light source, and the light intensity from the edge of the breeding barrel to the center is 250-1500 lux;

[0010] v) the breeding period is more than 45 days.

[0011] Preferably, the light conditions for breeding are obtained by screening the following method:

[0012] Screening the light intensity range and light quality conditions suitable for the growth of the red drum juvenile fish using a preference behavior experiment device, which includes a culture tank, a light source, video monitoring, a nano air ring, and a timing switch, and the entire experimental device is covered with a blackout cloth; an equilateral (e.g., 10 cm in length) hexagonal transparent column is placed in the central area (e.g., about 0.8 meters in diameter) of the culture tank, and six kinds of LED lights, i.e., red, blue, yellow, green, purple, and white, are arranged, and a wavelength tester (e.g., HPCS320 wavelength tester (Honggu, China)) is used to measure the LED light source, and at the same time, the height of the LED light from the water surface is adjusted, so that the light intensity from the edge to the center of the experimental tank is set to 250 to 2500 lux;

[0013] Before the start of the screening experiment, the red drum is placed in the experimental device for a period of time to adapt, and then the light source is turned on, and the distribution of the fish group is recorded by an infrared camera, and the experiment is continuously monitored, and after the experiment is completed, the water is changed, and the experimental fish is replaced to repeat the experiment; the number of fish groups appearing in each area is counted by playing back the video; the distribution percentage of red drum in different areas is calculated according to the formula: the distribution rate of experimental fish in a certain light quality area = the number of experimental fish in each area / 60 x 100%;

[0014] The distribution rate of red drum in each area is calculated, and the distribution rate is used to represent the preference of red drum to different light qualities, and the data is represented by mean ± standard error; the experimental data is analyzed and the significance of the difference between groups is tested.

[0015] More preferably, the test time of the above screening experiment is 8:00-18:00, and the red drum (e.g., about 60) is placed in the experimental device for about 30 min before the experiment starts, and then the light source is turned on, and the distribution of the fish group is recorded by an infrared camera, and the experiment is continuously monitored for about 10 h, and after the experiment is completed, the water is changed, and the experimental fish is replaced to repeat the experiment 3 times. The number of fish groups appearing in each area is counted by playing back the video, and the first 30 min is the stress period, and the number of red drum in each interval is counted every 5 min. After adaptation, the number of red drum distributed in each area is counted every 1.5 h, and each count is 6 times.

[0016] More preferably, the distribution rate data of the red drum in each area is represented by mean ± standard deviation (Mean ± SE), and the experimental data is analyzed by SPSS 27.0 software for one-way ANOVA, and the significance of the difference between groups is tested by Duncan method, and the significance level α=0.05.

[0017] More preferably, before the red drum juvenile fish is placed in the indoor culture tank for cultivation, it is first domesticated for 1-3 weeks to adapt to the new cultivation environment, and feed is used for feeding during the domestication period, and each day is fed twice in the morning and afternoon, and water and bottom cleaning are performed every day.

[0018] More preferably, the juvenile red drum is fed once a day at 08:00 and 16:00.

[0019] More preferably, the cultivation is carried out under a light intensity of 750-1500 lux.

[0020] More preferably, the cultivation is carried out under blue light irradiation with a main wavelength of 400-500 nm, more preferably 477 nm.

[0021] More preferably, the cultivation cycle is 45 to 60 days.

[0022] More preferably, the transparent column is made of acrylic plate.

[0023] The method of the present application is particularly suitable for screening the light conditions for juvenile red drum, and then carrying out cultivation to improve the body color and promote the growth of juvenile red drum.

[0024] Therefore, the present application can improve the growth and survival rate of red drum, and improve the brightness and redness value of the body color of red drum by analyzing the distribution characteristics of juvenile red drum under different light qualities and exploring the preference of juvenile red drum for light quality, so as to create a suitable light environment, obtain fast-growing, good-looking and high-survival juvenile red drum, and improve the economic benefits of aquaculture enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A schematic diagram of a device for detecting the light quality and light intensity preference of juvenile red drum.

[0026] Figure 2 Statistical diagram of light quality preference of juvenile red drum.

[0027] Figure 3 Statistical diagram of light intensity preference of juvenile red drum.

[0028] Figure 4 Cumulative survival rate of juvenile red drum under different light qualities.

[0029] Figure 5 Changes in body weight of juvenile red drum under different light qualities.

[0030] Figure 6 Changes in body length of juvenile red drum under different light qualities. EMBODIMENTS

[0031] The specific embodiment of the present application first screens the most suitable light environment for the growth and body color formation of red drum juvenile fish through the device of light quality and light intensity preference of red drum juvenile fish, and then breeds the red drum juvenile fish by arranging the most suitable light intensity range and the most preferred light quality above the breeding barrel of the red drum juvenile fish according to the screening results. The growth and body color formation of the red drum juvenile fish can be promoted under the most suitable light environment breeding condition for 45 days.

[0032] Unless otherwise indicated, the percentages described herein are by weight percent.

[0033] The following examples further describe and demonstrate illustrative embodiments within the scope of the present application. These examples are intended merely to be illustrative and should not be considered to be limiting of the application, as many variations of the application can be made without departing from its spirit and scope. Various modifications of the application in addition to those described herein will become apparent to those skilled in the art from the foregoing description and drawings. Such modifications are intended to fall within the scope of the appended claims.

[0034] Example 1:

[0035] The preference of red drum juvenile fish for different light qualities (red light, blue light, yellow light, green light, purple light and white light) and different light intensities (250-2500 lux) was determined. The specific steps are as follows:

[0036] 1) Installation of detection device: six pieces of acrylic plates with a length of 80 cm and a width of 10 cm were spliced into an equilateral hexagonal acrylic column with hot melt glue, and different colored glass papers were pasted on each side, respectively, red, blue, yellow, green and purple. The acrylic column with different colored glass papers was placed in the center of the experimental barrel, and a nano air stone ring was placed outside the acrylic column. A LED lamp with a power of 25W was used as the experimental light source, and the height of the lamp from the water surface was adjusted to set the light intensity from the edge to the center of the experimental barrel at 250-2500 lux.

[0037] 2) The distribution of the experimental fish was recorded by the camera.

[0038] 3) The water pump was used to add 30 cm high water from the water reservoir to the experimental barrel.

[0039] 4) Selection of red drum juvenile fish: 60 healthy and active red drum juvenile fish with uniform size were selected and placed in the detection device for 30 min.

[0040] 5) Light experiment: after 30 min, the LED lamp was turned on for 10 h of light experiment. The experimental test time was 8:00-18:00, and the water was changed after the experiment, and the experimental fish was replaced, and the experiment was repeated for 3 times.

[0041] 6) Data statistics: The number of fish in each area was counted by video playback. The first 30 minutes were the stress period, and the number of red drum in each area was counted every 5 minutes. After adaptation, the number of red drum in each area was counted every 1.5 hours, and the counting was repeated 6 times. The distribution percentage of red drum in different areas was calculated according to the formula: Distribution rate of experimental fish in a certain light area = number of experimental fish in each area / 60 x 100%

[0042] 7) Experimental results: Red drum juveniles showed a sustained movement response after the lights were turned on and randomly swam to each light source area. The statistical results showed that, whether in the stress period or the adaptation period, the distribution rate of red drum juveniles in the blue light area was the highest, reaching 36.34% and 28.51% respectively, and the distribution rate in the yellow light area was the lowest, reaching 3.41% and 11.05% respectively. There was a significant difference in the preference for different light qualities (P<0.05), and the preferred light intensity was 250-1500 lux.

[0043] Example 2

[0044] In order to optimize the light environment for red drum juveniles and improve their growth efficiency, according to the results of the color preference experiment, blue light with the highest distribution rate and yellow light with the lowest distribution rate were selected as the experimental groups, and white light was used as the control group. The light intensity was set to 750 lux, and a 60-day cultivation experiment was conducted to determine the light quality conditions that are beneficial to the growth of red drum juveniles, and to provide a theoretical basis for the adjustment of light environment for the healthy, rapid growth and welfare cultivation of red drum juveniles.

[0045] (1) The experiment was conducted in a light-proof compartment, and the light-proof cloth was used to cover the different treatment groups to avoid cross contamination of light sources between treatment groups and ensure the stability of light conditions in each group. Three groups were set up, namely blue light, yellow light and white light control group, and the light intensity was set to 750 lux. Three replicates were set up in each treatment group. At the beginning of the experiment, 60 red drum juveniles were placed in each experimental bucket, with an initial weight of 4.39±0.76g. The experimental period was 60 days. The light intensity was measured and calibrated every morning after feeding using a spectral illuminometer. The light cycle was controlled by an electronic timer and set to 10L:14D. The fish were fed twice a day at 08:00 and 16:00. To maintain water quality, water was changed and the bottom was cleaned twice a day. The amount of feed and the number of deaths were recorded every day. Every 15 days, 3 red drum were randomly taken from each experimental bucket (9 from each group), and their weight (g), length (cm) and color difference value were measured.

[0046] (2) Data analysis: The data results were expressed as mean ± standard deviation (Mean ± SD). The experimental data were statistically analyzed using SPSS 27.0 software. One-way ANOVA was used to compare the significance of the differences between the data using the new multiple range method (Duncan). A significant difference was considered when P < 0.05.

[0047] (3) Experimental results: The cumulative survival rate of redfin snapper juveniles in different light color groups decreased with the increase of experimental time, and the blue light group had the highest survival rate. During the experiment, the weight of the blue light group on the 45th day was significantly higher than that of the white light group and the yellow light group. The weight of redfin snapper juveniles on the 60th day showed significant differences among the three groups, from high to low, namely the blue light group, the white light group and the yellow light group (P<0.05). The body length of the blue light group on the 45th and 60th days was significantly higher than that of the other two groups, and there was no significant difference between the white light group and the yellow light group. The statistical results of the body color of each part of the redfin snapper juveniles at each experimental stage are shown in Tables 1-4. The blue light group had higher brightness and redness values, and there was a significant difference compared with the control group at the 30th day. The above results show that the use of blue light with a light intensity of 750 lux can achieve a good effect on promoting body color of redfin snapper juveniles for 30 days, and can also promote the formation of growth body color for 45 days.

[0048] Table 1 Effects of 15-day light exposure on the skin color of juvenile redfin snapper

[0049]

[0050] Table 2 Effects of 30-day light exposure on the skin color of juvenile redfin snapper

[0051]

[0052] Table 3 Effects of 45-day light exposure on the skin color of juvenile redfin snapper

[0053]

[0054] Table 4 Effects of 60-day light exposure on the skin color of juvenile redfin snapper

[0055]

[0056]

Claims

1. A method for improving the body color and growth of juvenile redfin snapper, characterized by: Juvenile redfin snapper were cultured in indoor culture tanks and fed with feed once in the morning and afternoon. Water was changed and the bottom was cleaned every day. The culture conditions were as follows: i) The aquaculture tank uses nano-air stones for continuous aeration, and the dissolved oxygen concentration is 6.5-7.4 mg / L. ii) The pH of the water in the culture tank is 7.5-8.4, iii) the water temperature and salinity in the culture tank were maintained relatively constant at 27.3-33.2°C and 25-31‰, respectively; iv) the culture tank was covered with a shade cloth, and the culture lighting conditions were set to a blue light source with a light intensity of 250 to 1500 lux from the edge to the center of the culture tank; v) The breeding cycle is more than 45 days.

2. The method for improving the body color and growth of juvenile redfin snapper according to claim 1, characterized in that: The lighting conditions for the culture were screened by the following method: A preference behavior experimental device was used to screen for light intensity ranges and light quality conditions suitable for the growth of juvenile redfin snapper. The preference behavior experimental device included a culture tank, a light source, a video monitor, a nano-aeration ring, and a timer switch. The entire experimental device was covered with blackout cloth. An equilateral hexagonal transparent column was placed in the center of the culture tank. Six types of LED lights, red, blue, yellow, green, purple, and white, were set. The LED light sources were measured using a wavelength meter. The height of the LED light from the water surface was adjusted so that the light intensity from the edge of the experimental tank to the center was set at 250 to 2500 lux. Before the screening experiment began, red snapper were placed in the experimental apparatus to acclimate for a period of time. Then, the light source was turned on and the distribution of the fish was recorded using an infrared camera for continuous monitoring. After the experiment ended, the water was changed and the experimental fish were replaced to repeat the experiment. The number of fish present in each area was counted by video playback. The distribution percentage of red snapper in different areas was calculated according to the formula: distribution rate of experimental fish in a certain light quality area = number of experimental fish in each area / 60 × 100%; The distribution rate of redfin snapper in each area was calculated and used to express the preference of redfin snapper for different light qualities. The data were expressed as mean ± standard error. The experimental data were analyzed and the significance of the differences between groups was tested.

3. The method for improving the body color and growth of juvenile redfin snapper according to claim 1, characterized in that: Before the redfin snapper fry are placed in the indoor breeding barrel for breeding, they are first acclimated for 1-3 weeks to adapt them to the new breeding environment. During the acclimation period, they are fed with feed once in the morning and afternoon, and the water is changed and the bottom is cleaned every day.

4. The method for improving the body color and growth of juvenile redfin snapper according to claim 1, characterized in that: The redfin snapper juveniles were fed once at 08:00 in the morning and 16:00 in the afternoon every day.

5. The method for improving the body color and growth of juvenile redfin snapper according to claim 1, characterized in that: The light intensity is 750 lux.

6. The method for improving the body color and growth of juvenile redfin snapper according to claim 1, characterized in that: The main wavelength of the blue light is 477nm.

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