Key Technical Points for Fish Rearing and Management in Winter

First, take advantage of the great opportunity of the Double Festival to sell fish that have reached marketable size as early as possible, so as to recover funds. If the aquatic product market has supply exceeding demand and prices are truly sluggish, fish can be held and temporarily kept in ponds to avoid the peak sales period. However, when selling marketable fish, you must control the timing well and not fall into the mistake of holding out for a better price like “marking the boat to seek a sword”; sell when it is time to sell, and strive to get a suitable price.

Second, use the winter slack period around the Spring Festival to calculate the year's production costs and carry out benefit estimates, and do a good job of the annual summary. From the annual summary, select the best farming models and production methods, and summarize successful experience and lessons from failure, so as to lay a solid material foundation for the new year's fishery production.

In addition, we also have the following work to do.

1. Overwintering management of marketable fish

Strengthen the feeding and management of marketable fish about to be sold, especially do a good job of anti-theft work, and absolutely do not let a moment of negligence turn into an incident and create “a bumper harvest without a bumper income”.

2. Overwintering management of fingerlings

Strengthen management during the overwintering period of fingerling production, deepen the pond water, and do a good job of pond merging for overwintering.

3. Fish pond excavation and planning

Carry out comprehensive planning and design for newly excavated fish ponds, and choose locations with convenient water intake and drainage, excellent water quality, and convenient transportation.

4. Do not miss the fishing season; complete pond desilting and repair work in a timely manner

In recent years, some fish pond contractors have only valued immediate benefits, putting effort into stocking, feeding, fertilizing, and other aspects, while neglecting necessary desilting work. Year after year, the sludge at the pond bottom accumulates thicker and thicker. The sludge thickness in ordinary ponds is around 40cm, and in some intensive culture ponds and ponds near villages and towns, the siltation thickness is even greater, leading to deterioration of the pond's ecological conditions. Its main disadvantages are as follows:

1) It makes the pond shallower, reduces water storage capacity, and shrinks the water space for fish to live in, directly affecting fish yield per unit area.

2) It causes oxygen deficiency in the pond water body. Because the sludge contains large amounts of inorganic matter. In the high-temperature seasons of summer and autumn, under the action of bacteria, inorganic matter oxidizes and decomposes, continuously consuming large amounts of dissolved oxygen in the water, often exhausting the already limited dissolved oxygen in the lower layer of the pond water and creating an oxygen-deficient state. Under oxygen-deficient conditions, anaerobic bacteria multiply in large numbers and produce ammonia, hydrogen sulfide, inorganic acids, and other substances harmful to fish. These substances are also strongly oxygen-affinic, causing the pond water to carry an “oxygen debt”. At night, due to convective exchange between the upper and lower layers of pond water, dissolved oxygen in the entire pond water body becomes insufficient, and pond fish float to the surface due to oxygen deficiency. If there is continuous rainy weather, low-pressure muggy heat, thunderstorms, or the rise of a north wind and other adverse weather, then oxygen deficiency in the fish pond becomes even more serious, and fish kills from pond turnover are extremely likely to occur.

3) The large amount of nitrogen-containing inorganic matter in the sludge, whether undergoing aerobic decomposition under the action of nitrite bacteria or anaerobic decomposition under the action of nitrifying bacteria, ultimately produces ammonia in both cases. Ammonia is highly toxic; even at very low concentrations, it inhibits the growth of fish and other aquatic organisms.

4) Many fish parasites and pathogenic microorganisms exist in the sludge. When pond water quality deteriorates, acidity increases, and conditions worsen, the disease resistance of fish decreases, while pathogenic microorganisms and the like multiply and spread in large numbers, leading to outbreaks and epidemics of fish diseases and causing losses. In recent years, the frequent outbreaks of diseases in silver carp, bighead carp, and other fish in small ponds and reservoirs are directly related to severe pond siltation.

According to observations, siltation in fish-rearing ponds generally increases at a rate of 5-10cm per year. In intensive culture ponds and ponds near villages and towns with domestic sewage inflow, the siltation rate is even faster. Pond siltation has become one of the important factors limiting fish yield in pond aquaculture. For pond fish farming to maintain stable and high yields continuously, summer desilting work must be done ahead of time.

5. Production arrangement

According to market demand, choose farming models and farming species flexibly according to local conditions, reasonably arrange stocking plans, and stock fingerlings in a timely manner. Many farmers are accustomed to stocking after the Spring Festival, but in fact doing so is not scientific. Spring temperatures gradually rise, fish scales become loose, and due to netting, transportation, stocking, and other reasons, fish bodies are easily injured, affecting the survival rate of fingerlings. Friends who want to farm grass carp can inject grass carp vaccine for grass carp fingerlings at this stage.