Methods and techniques of two-crop continuous culture of tilapia

Two-crop tilapia continuous culture model: graded large size tilapia fry, in the adult fish culture pond with a certain number of filter-feeding silver carp, bighead carp and herbivorous grass carp, carnivorous herbivorous herbivorous herring, pure feeding culture together. When tilapia meets the market specifications, it will be caught and sold, and the farmed fish will be sold according to the size of the specifications. The second crop of large size tilapia is released in the non-dry pond immediately, and the dry pond is carried out after the tilapia reaches the market specifications. What is said above is that the continuous culture technology of two crops of tilapia is a culture model summed up according to the successful experience of tilapia farmers in Gaozhou City, Maoming in recent years. The pond is clear only once for two crops of tilapia.

This culture model makes full use of pond culture space, saves culture time, returns funds quickly, the products meet the export healthy culture standards, and can improve the economic benefits of mixed culture of silver carp and bighead carp, and relatively reduce the rental cost of tilapia ponds. Increasing tilapia production per unit area is the preferred culture mode for pure feed farmers of tilapia in Gaozhou City, Maoming, according to local characteristics. In general, tilapia can survive the winter naturally, professional fishing teams and other conditions can make use of this culture model and produce good economic benefits. This culture model is introduced as follows:

Prerequisites for continuous cultivation of one or two crops

1. Adult fish culture ponds

Adult fish culture ponds do not require very regular, silt less than 20 cm, an area of 5cm 40 mu, a water depth of 1.5m 4m, flat bottom, easy to catch ponds or small mountain ponds, generally require 5cm 10 mu water surface with 2~3kw oxygen equipment. The conditions of the bottom of the adult fish culture pond, such as the depth of silt and the flatness of the bottom, have a great influence on the starting rate of tilapia. if the bottom is uneven, it is difficult to achieve a higher starting rate, which will leave a large number of tilapia in the first crop, so it is not suitable for two crops of tilapia.

2. Seedling selection of tilapia.

Tilapia fry can be tilapia, tilapia can also be Oreochromis niloticus, but requires fast growth, high male rate, high catch rate, the most suitable for two crops of tilapia. In order to ensure the quality of tilapia fry, farmers had better choose the fry of tilapia with good reputation.

3. Coarse culture of large size tilapia seedlings by graded standard.

The graded standard of tilapia culture can make full use of the culture water space, save the pond rent, and is easy to raise and manage. The two-crop culture is generally divided into one to three grades, and the fry of tilapia from 1.5~3cm is raised to the large size tilapia with 100~200g/ tail. The area ratio of fry culture pond to adult culture pond is 1, 3, 1 and 8, and the large size fry is generally cultivated 2-4 months before the release of fry in adult culture pond, so as to ensure the normal supply of large size fry in adult fish culture. The standard coarse stocking density depends on the specifications of the seedlings to be cultivated, the size of the cultivation pond and the cultivation conditions. The general stocking density is 600015000 / mu, and the cultivation method is the same as that of general tilapia. It is best to cultivate the fry with fertilizer and water to ensure that the fry has enough open food after entering the pond and improve the survival rate of the fry. Farmers with insufficient or no nursery ponds can also directly purchase large-size tilapia species for adult fish culture.

4. pure feeding adult fish culture.

The two-crop continuous culture model is suitable for pure feeding tilapia culture. Other three-dimensional culture (using livestock manure culture) because livestock and fish produce a lot of excrement, which is easy to cause water quality deterioration, tilapia growth rate is slow, each crop culture cycle is too long, tilapia self-propagating too many small fish is not suitable for two-crop tilapia culture mode.

2. Preparation before stocking

Seven days before the first stocking, dry cleaning the pond with 80~100kg/ quicklime per mu to ensure that all tilapia or other fish die in the pond. After three days, more than 1 meter of water is filtered into the pond with a 60-mesh bag, and large larvae can be released when the water quality pH value is less than 8.6, and the adult fish culture does not need fertilizer water.

3. Stocking of seedlings

The stocking density of tilapia adult fish ponds depends on the conditions of the fish ponds and should not be too dense. The general stocking density of this culture model in Maoming area is 1000 / mu tilapia, 20 / mu bighead carp, 20 / mu silver carp, 20 / mu grass carp and 3 / mu herring (bighead carp and silver carp should be stocked with fish larger than 500g/ tail if they are caught in the first crop, and the number should be controlled below 20 / mu in order to reach the relatively large market specification).

IV. Input and feeding management

Feeding management is an important part of tilapia culture, which has an important impact on cost saving and disease reduction. The feeding management of two crops of tilapia in Maoming area is as follows:

1. Feeding method

No matter floating material or submerged material, it is suitable to use feeder, which can save labor and achieve the effect of uniform feeding of tilapia. A pond of 515 mu is equipped with a feeder, and a pond of 15 mu is equipped with more than two feeder machines, so that the feeding coverage area is large enough to ensure uniform feeding of tilapia, so that the fish specifications will not be polarized, and the fish specifications out of the pond will be relatively neat.

2. Feeding times and feeding quantity

Generally, the feeding frequency is twice a day, and the daily feeding time is 8: 00 in the morning and 17: 00 in the afternoon, accounting for 0.8-6% of the fish's body weight, depending on the weather, fish specifications, water quality, water temperature, food intake, and the trend of fish price. Adequate sunshine, strong wind, good wind direction, suitable water temperature, good water quality can be fed enough; low pressure, low temperature, cloudy and rainy days, before typhoon, when the water quality is bad, feed less or not. In short, feeding should not only ensure the nutritional needs of farmed fish, but also not waste feed and cause water pollution.

Due to the different feeding intensity of different tilapia species, Gefu tilapia still ingest normally when the water temperature is 16 ℃, but the feeding rhythm of Oreochromis niloticus is very low, because the digestibility of tilapia is not high at low temperature, and farmers should control the feeding amount according to the actual situation. According to many years' farming experience, tilapia farmers in Gaozhou fed more than 200g tilapia with 812g bait every day under normal weather, water temperature and water quality.

3. Feed selection

Adult fish culture feed is generally nutritious and fresh. The feed of large tilapia farmers in Maoming area is generally self-made to ensure the quality.

V. Management and disease control

1. Water quality management

Turn on the aerator properly to keep enough dissolved oxygen in the water. Generally in good weather conditions every day at noon and early morning aerator 2-4 hours, bad weather or poor water quality of the case to increase start-up time, 4-10 hours a day. Keeping dissolved oxygen for 24 hours was greater than 4mg/L. Change the water 10-40 cm per month, keep the pool water "fat, alive, tender and cool". In hot summer or cold winter, it is appropriate to keep the water depth of 2-3 meters, and sprinkle lime water at 10-15 kg per mu of quicklime once a month. EM bacteria, substrate regulator, etc. are used in accordance with the product instructions.

2. Control of the second generation of tilapia seedlings.

Self-propagation will occur when tilapia is cultured for a long time, and too many seedlings cause the problem of waste of feed. 30,40 30g/ tail fish per mu can be released in the middle of the first crop culture to solve the problem of excessive self-propagation of tilapia, and to ensure the success of tilapia culture in the second crop.

3. Prevention and treatment of fish diseases

The density of tilapia culture in Maoming area is not large, and the disease is rarely occurred in the mode of two-crop continuous culture. Pay attention to the cleaning and disinfection of ponds before stocking, water quality control, feeding management and other conditions, generally do not occur major diseases. Streptococcosis of tilapia has occurred frequently in recent years. Enrofloxacin can be used as a mixture: 10~20mg per kg of fish body weight per day, once a day for 5 days, water temperature above 18 ℃, withdrawal period for 10 days.

VI. The first crop of tilapia fishing on the market

Tilapia culture to the market specifications, appropriately lower the water level (1-1.5 meters), for the first fishing on the market, once again lower the water level (0.5 meters), as far as possible to catch tilapia on the market, the general tilapia catch rate of more than 90%. If the specifications of other matching fish such as silver carp and bighead carp do not meet the listing requirements, they will continue to be cultured in the original pond and raw fish, and the first crop of tilapia on the market will only take up to four days. The time of breeding is greatly saved.

VII. Management of fry and culture of tilapia in the second crop

After the first crop of tilapia on the market, you can enter the water into the pond on the same day, and the large size tilapia can be released when the water level reaches more than 0.7 meters. The stocking density is similar to or less than that of the previous crop, and the breeding of silver carp and bighead carp depends on the situation. If the silver carp and bighead carp are not on the market last time, the management of tilapia culture is the same as the routine.