Handling Methods and Key Technical Points Before Fry Stocking

Today's fish farmers basically fatten their fish from fry, so the fry generally have to go through long-distance transport before reaching the farm. Once these fry arrive at the farm, they cannot be put directly into the pond; they need to be handled first, otherwise large-scale fry deaths are likely to occur.

1. Disinfection of Seed Stock

Because the fry are kept in stagnant water for a long time during transport and their density is relatively high, bacteria and pathogens easily breed along the way. The first thing to do after the fry arrive is to prepare a seed stock soaking solution and introduce the fry into it for disinfection, so as to ensure their safety. Of course, other safe disinfectants can also be used, such as salt water and the like, but the concentration must be carefully controlled, especially the concentration of the salt water, which must not exceed 3%.

2. Feeding

After disinfection, it is time to prepare the feeding; after all, no food is given to the fry during transport, so once they reach their destination they need to replenish nutrients immediately. Egg yolk water is the first choice for feeding: mix cooked egg yolks with water and stir well until the mixed water looks only slightly pale yellow, and just a few eggs can meet the food needs of several hundred thousand fry. This is also to help the fry survive better in the unfamiliar environment they are about to enter; once the fry are full, after being released they can spend more time searching for food.

3. Adjusting Water Temperature

Once feeding is complete, it is time to prepare for release, but they cannot be released yet; the water temperature of the current tank holding the fry must first be adjusted. Generally, the water in the pond is much lower in temperature than the place where the fry are currently living. If they are released rashly, the fry may fail to adapt to the water temperature of the new pond and develop a stress reaction, which in severe cases can lead to injury or death. Therefore, the pond water should be slowly poured into the current tank holding the fry until the temperatures on both sides are close, and only then should they be released.

4. Release

Release is also a relatively critical step. Many farmers are used to pouring the fry straight out from the air, or getting into the water and then quickly tipping the fry out, all of which easily injure the fry. The proper way is to slowly immerse the container holding the fry into the water, then slowly withdraw it from the bottom, letting the fry complete the change to their natural growing environment under gentle conditions.

Fry are actually quite fragile, so all actions before release should preferably be a little gentle and slow; this not only avoids harming the fry but also avoids stressing them. Larger vibrations or noises will make the fry dart about everywhere, causing unnecessary losses.