CATDOLL : CATDOLL: Asking: How to distinguish the male and female of [Glossy Lip Grouper], also known as: Freshwater Grouper. As far as I know, it lives in flowing streams with good water quality.

1. Generally speaking, female grouper fish of the same age from the same origin are always larger than male grouper fish, while male grouper fish are larger in size.

2. The body color of male fish is much more beautiful than that of female fish.

3. During the reproductive season, gently press the fish's belly. If you can feel eggs flowing out of the reproductive hole, the fish is female.

There is milky white semen flowing out of the reproductive opening, so this fish is definitely a male.

You can observe and determine according to the above method. You can also refer to the reference materials I provide for you to discuss in depth. It is quite difficult to distinguish young fish. It requires long-term experience accumulation.

Adult smoothlip fish have vertical stripes that clearly indicate males, while those with horizontal stripes (stripes like small fish) are clearly females.

In order to explore the artificial propagation and seedling cultivation technology of freshwater grouper and solve the "bottleneck" problem of seedlings that restricts the promotion of freshwater grouper breeding, we carried out artificial propagation and seedling cultivation experiments of freshwater grouper in 2004 and achieved ideal results. The experimental results are summarized as follows:

1. Test conditions and methods

1. Artificial breeding

(1) Pond conditions: The experimental ponds are located in the Jiangsu Modern Fishery Science and Technology Demonstration Park (Xishan). There are two experimental ponds, each with an area of ​​1 mu. The ponds are numbered 5 and 6. The pond depth is 1.8 meters, the water depth is 1.5 meters, the silt is about 5 centimeters, the pond bottom is flat, the water quality is fresh and pollution-free, and the water inlet and outlet are convenient.

(2) Broodstock cultivation: The broodstock used for this breeding were selected from commercial fish raised by the company in 2003. They were transferred to a greenhouse cement pool for cultivation in early November 2003. There was one greenhouse cement pool with an area of ​​35 square meters. The average size of the broodstock was 0.50 kg per tail, and the number was 70. During the greenhouse cultivation period, they were fed with snails and mussel meat, and granular feed to promote the development of the gonads of the broodstock. On May 8, 2004, the broodstock were released into an outdoor artificial breeding test pool. Through further intensive cultivation, their gonads matured in early June.

(3) Identification of the sex of broodstock: For broodstock with mature gonads, the male fish has a darker body color, and milky white semen flows out when the abdomen is squeezed; the female fish has a lighter body color with yellow tints, and the pelvic fin is located at the pectoral position and the caudal fin is round-shaped. It has a reproductive process, and the eggs are not easy to squeeze out.

(4) Induced spawning and hatching: 16 females and 17 males were stocked in ponds 5 and 6 respectively. When the gonads of the broodstock matured, the pond water was replaced in large quantities on June 6 to induce the broodstock in the pond to basically achieve synchronous spawning and fertilization without the need for injection of induced spawning drugs. The spawning habits of freshwater grouper are similar to those of tilapia. First, a nest for spawning is dug at the bottom of the pond. Spawning is basically in the afternoon. After spawning, the female guards the fertilized eggs, and the male helps guard them. The eggs are oval, dark yellow-green, opaque, and sticky. The eggs are scattered in the nest. A female weighing about 500 grams can lay 19,000 to 24,000 eggs each time. When the water temperature is around 25°C, the fertilized eggs can hatch into fry after 56 hours. After the fry are hatched, the parents should be caught in time to prevent them from being eaten. Freshwater grouper fry that have just hatched are about 0.6 cm long and move constantly at the bottom of the pond. When the water temperature is around 26°C, the yolk sac disappears one week after hatching, and the fry swim to the upper water layer of the pond and no longer cluster at the bottom. After the yolk sac disappears, the fry are promptly caught and taken to the summer flower cultivation pond for seedling cultivation.

2. Seedling cultivation

(1) Pond conditions: There are two ponds, numbered 14 and 15, each with an area of ​​5 mu. The pond is 2.0 meters deep, the water depth is 1.6 meters, and the silt is about 10 centimeters. The ponds are easy to drain and inlet. Each pond is equipped with a water pump and an aerator.

(2) Pond cleaning and disinfection: Half a month before stocking fry, use 150 kg of quicklime per mu to clean the pond using the dry method to kill harmful organisms and pathogens in the pond.

(3) Cultivation of basic bait: One week before stocking, add 250 kg of fermented organic fertilizer per mu, then fill with water to a depth of 0.6 m. Use a 60-mesh screen to filter the water inlet to prevent harmful organisms from entering the pond. One week later, when the growth of cladocerans, copepods, rotifers, etc. in the pond reaches its peak, it is the best time to stock the fry.

(4) Stocking of fry: On the morning of June 16, fry were hauled from the breeding pond to the seedling cultivation pond. The water temperature of the pond was about 26°C when the fry were released. 281,700 fry were released into each pond. The specifications for stocking in the same pond were consistent, as fry with large differences in size would kill each other.

(5) Scientific feeding: In the first three days after freshwater grouper is put into the pond, no additional feed is needed because the basic bait in the pond is rich. On the fourth day, soybean milk, feed yeast and juvenile pellets are added. After about 10 days of cultivation, when the fry reach more than 1.8 cm, they can be tamed. At this time, fish paste can be fed. After 3 to 4 days, a small amount of artificial compound feed is added to the fish paste and fed. Later, the proportion of compound feed is gradually increased, and the amount of fish paste is reduced, until all compound feed is used for feeding. Feed once in the morning and afternoon every day, at 8 to 9 am in the morning and 4 to 5 pm in the afternoon. The daily feeding amount is 23% to 28% of the body weight of the fish in the pond.

(6) Water quality management: Putting fry in shallow water can increase the density of bait per unit water in the pond, which is beneficial for fry to feed, and can also increase the water temperature in the pond, which is beneficial for the rapid growth of fry. As the fish grow, the water level is gradually deepened. After two weeks, the water depth is increased to 1.5 meters. After that, the water is changed every 5 days or so, and the amount of water changed each time is 1/5 to 1/4 of the pond water.

(7) Daily management: Patrol the pond three times a day, morning, noon and evening, to observe the fish fry's eating, activities and changes in pond water color. Turn on the aerator between 4 and 6 a.m. and regularly measure changes in dissolved oxygen and pH value, so as to adjust the amount of feed in a timely manner and do a good job in fish disease prevention and control.

2. Test results

1. Induction and incubation

66 broodstock were induced to spawn, including 32 females and 34 males. A total of 702,000 eggs were laid, with an induced spawning rate of 97%, a fertilization rate of 96.1%, 624,600 fry hatched, a hatching rate of 92.6%, and a total of 563,400 fry emerged.

2. Seedling cultivation

After 28 days of cultivation, a total of 452,400 freshwater grouper summer flower fingerlings were bred, with a survival rate of 80.3%. The average size was over 3.0 cm. Among them: 254,100 summer flower fingerlings were released from Pond No. 14 with a survival rate of 90.2%, and 198,300 summer flower fingerlings were released from Pond No. 15 with a survival rate of 70.4%.

3. Summary and Discussion

1. The broodstock for artificial breeding this time reached sexual maturity at the age of 2. Since freshwater grouper cannot tolerate low temperatures, the broodstock were moved to a greenhouse cement pool for cultivation in early November 2003. During the wintering period, the feeding of snails and mussels, appropriate amounts of compound feed, suitable temperature and oxygenation facilities effectively promoted the gonadal development of the broodstock, and brought forward the time for seedling rearing.

2. Since artificial breeding of freshwater grouper does not require the injection of oxytocin, it only requires a large amount of replacement of pond water to change environmental factors to encourage them to ovulate and sperm uniformly, leading to natural fertilization. This natural fertilization method greatly improves the fertilization rate and hatching rate.

3. Freshwater grouper is a carnivorous fish, especially in the fry stage. Its carnivorous characteristics are quite obvious, mainly feeding on zooplankton. Therefore, one week before stocking, the basic bait must be cultivated, which is the key to improving the survival rate of the fry. In addition, the feed must be well-fed, and the specifications of the fry in the same pond must be uniform. The No. 14 breeding pond has a survival rate of 90.2% due to its uniform specifications, while the No. 15 breeding pond has uneven specifications, resulting in the killing of fry by fry, and the survival rate is low, only 70.4%. Therefore, the specifications of the fry in the same pond must be uniform.

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