CATDOLL : CATDOLL: How to stock fish fry and fingerlings, and how to identify good and bad fry?

How to stock fish fry and fish fingerlings, and how to identify the quality of fish fry?

The small fish that have just hatched from the eggs are called fry. When the fry grows up, they are called fish. 1. How to identify the quality of fry and fish species There are usually two ways to observe the quality of fry: one is to put the fry in a basin. If it twists violently, the body bends more severely, and can last for a certain period of time, such fry is a manifestation of a relatively strong physique; on the contrary, if the twisting is not violent, and only twists for a short while and then stops, it means that the fry is in poor physique.

Fish species with strong physiques like to live in groups, move actively, and immediately sink into the water when startled; they are always ahead when looking for food or swimming upstream; they have bright colors, smooth muscles, and jump wildly in the basin. Fish species with poor physiques often move in scattered groups, move slowly, are not sensitive to being startled, are thin, have congested bodies due to injuries, and do not jump actively in the basin.

2. How to stock fish fry "Fertilize the pond" is an important part of stocking fish fry. The so-called fertilized water means the water color is oily green. If you find that the pond water is not fertile 3-4 days before stocking fish fry, you should apply fertilizer as soon as possible. Fertilization should not be applied too early, because if fertilization is applied too early, many large zooplankton will grow, which is not conducive to the swallowing of fish fry; on the contrary, if fertilization is applied too late, after the fish fry are put into the pond, the lack of bait organisms will affect the growth of the fish fry.

(I) Stocking density Whether the stocking density is reasonable will directly affect the growth of fry. If the density is too high, the fry will grow slowly and the survival rate will be low; if the density is too low, although the fry will grow fast and the survival rate will be high, it will waste water surface and the cost will be high. Therefore, the density must be determined according to the pond conditions, fertilizer sources and fry types. Usually, it can be stocked according to Table 51.

(II) Precautions for stocking fish fry 1. The best time is 9-10 am or 4-5 pm. At these two times, the water temperature is suitable and the oxygen is sufficient, which is conducive to the survival of fish fry. 2. Location The location for stocking fish fry should be selected in the upwind of the pond water. The water quality here is fresh, which can prevent the fish fry from being washed to the edge of the pond and causing death. 3. Method When stocking fish fry, first open the water surface with higher water temperature above the stove, then bring the fish bucket close to the water surface, and then gently pour the fish fry into the water.

3. How to stock fish fingerlings Fish fingerlings can be divided into the following categories due to their different growth times: fry that are raised for 20 days to 1 month are called "summer flowers", fry that grow to 6-9 cm are called "winter flakes", and fry that grow to the spring of the second year are called "spring flakes". The following points must be noted when stocking fish fingerlings:

(i) Early stocking of fish It is more suitable to stock fish around the Spring Festival. At this time, the water temperature is lower, the fish are strong, the scales are tight, and they are not easily injured by netting, and the survival rate is high. It is also conducive to making full use of the high temperature season from June to August to accelerate growth. (ii) Good seed quality The so-called good seed quality, in addition to strong physique, also requires attention to stocking large-sized species, generally 12-15 cm long. Fish of the same age and species are required to be of the same size, with similar length and weight. The stocking rate per mu (iii) Good combination can be determined according to water source, water quality and bait conditions. The answer is 500.

The proportion of fish. Under normal circumstances, in areas with abundant water resources, good water quality, and conditions for feeding and fertilization, 600 to 900 fish species over 9 cm in length can be stocked per mu of pond. Among them, silver carp and bighead carp can account for 40-50%; grass carp and crucian carp can account for 30-40%; silver carp and crucian carp can account for 10-20%. If the water source is poor, but the water level can be maintained and the water quality is relatively fertile, 400 fish species over 9 cm in length can be stocked per mu without feeding or fertilization. Among them, silver carp and bighead carp should be reduced, and the proportion of grass carp, silver carp, carp, and crucian carp can be appropriately increased.

4. Disinfection Before stocking fish, it is very important to disinfect the fish. You can use 10ppm bleach solution to soak the fish for 20-30 minutes to eliminate bacterial skin diseases and gill diseases; you can also use 3-5% salt water to soak the fish for 5 minutes to prevent and treat saprolegniasis and rotifer disease.

(V) Strengthen management. After stocking fish, pay attention to timely feeding and fertilization. You can put some tender grass fragments for grass carp, and some broken snails, etc. for black carp and carp. You can also put some bran, chaff, etc. into the water. However, if the water is too fertile, you cannot fertilize. Check before dawn every day. If the fish head floats on the water for a long time, it means that the water is too fertile; if the fish head floats on the water and opens its mouth to swallow air, it means that there is a lack of oxygen in the water. At this time, you must inject clean water in time. In addition, you must pay attention to drought prevention, leakage prevention, disease prevention, and preventing the breeding fish from hiding and escaping.

Which season is best for releasing fish fry?

The period from late May to mid-June is the best time to stock fish fry.

One or two months after the New Year, or in July or August, can also be done.