Cage culture of loach is highly profitable, a good aquaculture project
Loach is delicious and nutritious, known as the "ginseng" of the water, and is an excellent fish. In recent years, wild loach resources have declined, and market supply falls short of demand. Therefore, developing artificial loach farming has broad prospects. Years of production practice have proven that cage culture of loach has the advantages of low investment, quick results, high yield, convenient management, easy harvesting, and significant economic benefits, making it a practical farming technique worth promoting.
1 Materials
1.1 Pond A 15667 sq m pond, water depth 1.5 m, pond mud thickness 15 cm, rectangular, oriented east-west, with inlet and outlet set at opposite corners of the pond. The water source is river water, fresh in quality, with transparency of 30 cm, pH value 7.5, and dissolved oxygen content of 605 mg/L.
1.2 Cage materials, specifications and setup The cages are made of polyethylene, twisted silk net type, with the cage frame built from bamboo poles, fixed directly in the water. Loach farming cages are divided into fingerling rearing cages and adult loach holding cages. The mesh size of fingerling rearing cages should be such that the fry cannot escape, with a cage body area of 10-25 sq m. The mesh of adult loach holding cages is 0.5-1 cm, with a cage body area of about 50 sq m. The cage height depends on the farming water body, generally with the upper part of the cage extending 40 cm above the water surface. Loach does not like strong light, so cages should be set in shallow water at the edge of the lake, with 15-25 cm thick mud spread on the cage bottom.
2 Methods
2.1 Pond clearing and preparation
On April 2, 2012, 150 kg of quicklime per mu was used at 1 m water depth, slaked into slurry and splashed over the entire pond.
2.2 Cage placement
On April 15, the newly made cages were soaked in a 20 mg/L potassium permanganate aqueous solution for 20 minutes, then placed in the pond water to soak for about half a month, allowing a layer of algal biofilm to attach to the net surface, making it soft and smooth, while also removing harmful substances from the new netting, to avoid skin abrasions or disease in the loach. On May 3, cage placement began, with the 8 upper and lower corners of each cage fixed with bamboo poles, the cage bottom about 25 cm from the pond bottom, and the upper edge of the cage more than 50 cm above the water surface, with row spacing of 5 m and interval spacing of 1 m, to facilitate feeding management and water exchange.
2.3 Transplanting water peanut, alligator weed or water hyacinth
From May 10 to 15, about 10 tonnes (wet weight) of water peanut, alligator weed or water hyacinth was collected from clean rivers and placed in the cages, covering 70%-80% of the area. On May 18, 10 kg of urea per mu was dissolved in water and splashed to promote rapid growth of the water peanut, alligator weed and water hyacinth.
2.4 Seed selection and stocking
The fry sources for cage loach farming include artificially bred fry and wild fry. Artificially bred fry have a high survival rate in farming and gain weight quickly, but the fry cost is high; wild fry have low cost, but the farming survival rate is relatively low and weight gain is slow. Before stocking, the fry are soaked in a 1×10E-5 concentration potassium permanganate solution for 10-30 s, or soaked in 3%-5% salt water for 10-20 seconds, to kill surface pathogens and surface parasites, and at the same time, injured and weak fry are removed. Fingerling rearing cages are stocked with 30000 loach fry of 3-5 cm body length per sq m. When the loach grows to 10-15 cm body length, they are transferred to adult loach holding cages, with a stocking density of 1500-2500 fish per sq m. The specific stocking density for fingerling cages and adult loach cages should be determined according to conditions such as water body fertility, whether there is flowing water, loach size and constitution, and the level of feeding technology. If the water quality is fertile and fresh, there is slight flowing water, the loach size is uniform and the constitution is good, and the feeding conditions and technology are relatively good, the stocking density can be appropriately increased.
2.5 Food selection and feeding
Loach has a very broad diet; besides feeding on natural food organisms, it also feeds on artificially prepared feed. Cage loach farming mainly relies on artificial feeding, and the feed given includes rice bran, soybean cake, wheat bran, fish meal, live bait and compound feed, etc. Artificial compound feed is made from soybean cake, rapeseed cake, fish meal, silkworm pupa powder and pig blood powder, etc., in which the ratio of animal to plant feed is 6:4. If the water temperature rises above 25°C, the proportion of animal feed in the compound feed should be increased to 80%. Feeding should follow the "four fixed" principles: fixed time, loach has obvious feeding peaks within a day and night, respectively 6:00-9:00 and 16:00-18:00; fixed location, feed is given at fixed points, which can help loach form a habit of concentrated feeding, and also facilitates manual observation of loach feeding so that the feed amount can be adjusted in time; fixed quality, do not feed spoiled or rotten feed, keep the feed fresh and its composition relatively stable; fixed quantity, the daily feeding amount should be adjusted at any time according to the loach's growth condition, water temperature, water quality, etc., generally based on being eaten up within 1-2 days. Loach feed intake is greatly affected by water temperature; within the suitable growth water temperature range, the daily feeding rate is about 4%, and generally the most suitable feeding amount is that which is eaten up within 1 hour. Loach has a relatively large feed intake at night, and also feeds during the day during the vigorous growth period; based on this characteristic, feeding should mainly be done in the evening. Because loach has the trait of being greedy, excessive feeding should be avoided during farming. When the water temperature is above 30°C or below 12°C, the loach's appetite decreases, and at this time feeding should be reduced or stopped.
2.6 Daily management
Water quality management is the same as conventional fish farming; after loach fry are put into the cages, they are not fed for 1-3 days. From the 5th day, training feeding begins with 50% earthworm, 10% complete feed for yellow eel, and 40% silver carp and bighead carp minced into fish paste, kneaded into balls and fed at fixed points. As the feeding amount increases, the proportion of earthworm is gradually reduced, and the amount of silver carp and bighead carp and complete feed is increased, reaching 20% earthworm, 15% complete feed, and 65% silver carp and bighead carp. After successful feeding training (feed intake reaching 3%-4%), medicated bait is started, first with the deworming drug "Yuchongqing" taken orally for 3 consecutive days, then with the antibacterial drug "Baidu Granules" for 3 consecutive days. Every 15 days, 20 kg of quicklime per mu and water disinfection drugs such as strong chlorin are used alternately for disinfection. On August 15 and September 10, microecological preparations were used once each to purify water quality and adjust the microecological balance. Inspect morning and evening every day to check whether the cages are damaged and whether loach activity is normal. In the high-temperature season from July to August, when the water surface covered by water peanut accounts for 1/2 of the cage area, excess water peanut in the cages should be removed so that it covers about 1/3 of the cage area. Loach has relatively strong disease resistance, and coupled with strict screening when purchasing fry, basically no diseases occur, but during the farming process, work such as disease prevention and treatment medication for the pond should still be done well. On November 20, dried weeds were covered over the cages to keep warm for overwintering.
3 Results
3.1 Yield
Harvesting began on October 18 and cages were combined for overwintering, with a yield of 3500 kg, a net increase of 1240 kg, and a survival rate above 80%.
3.2 Benefit analysis
Sold around the Spring Festival, the average price of loach was 40 yuan/kg, sales revenue was 160000 yuan, minus 65000 yuan invested in yellow eel fry, feed, etc., the income was 95000 yuan, with an average net benefit increase of 1020 yuan per cage, and an input-output ratio of 1:2:5.
4 Discussion
(1) The time for stocking fry should avoid the peak spawning period, because during this period loach fry are injured by catching, transport and stocking, affecting the survival rate. In the Huaibei area, it is generally more suitable to release fry from the end of June to mid-July.
(2) Feed quality should be based on the feeding habits of loach fry, choosing feed that can be fed for a long time and has low cost and high meat gain rate. For example, 10% earthworm, 40% silver carp, and artificial compound feed can account for 50% of the feed. The feeding amount must be sufficient and not intermittent; it is best to have a small amount of leftover feed. Feeding should be at fixed times, generally around evening. In the vigorous feeding months of August to September, bait should be given twice daily, once at 8-9 a.m. and once at 4-5 p.m. Feeding should be at fixed locations, with feed kneaded into balls and placed on water peanut, alligator weed or water hyacinth, generally setting 1 feeding point per 4 sq m, feeding at multiple points to reduce competition for food and make the loach grow evenly.
(3) Choose opening feed that loach likes to train feeding. Wild yellow eel mainly feeds on aquatic insects, earthworms, shrimp and other fresh live animal feed. Artificial loach farming starts mainly with earthworms and river mussels, gradually increasing the proportion of artificial compound feed and fresh fish paste; this way the feeding training time is short and results are quick, which is conducive to rapidly increasing feed intake.
(4) Promptly remove residual bait from the feeding table and keep the water quality in the cages fresh. The cage specification should preferably be 2 m × 6 m × 1.5 m; if too wide, it is not conducive to water exchange inside the cage, nor to feeding and removing residue.
(5) Frequently brush the netting to maintain water circulation inside and outside the cage. Keeping the water quality in the cage lively and fresh helps plankton enter the cage. Check the cages in time and repair any holes immediately to prevent loach from escaping and harmful organisms from entering the cages. At the same time, cages should be equipped with covers and other anti-escape facilities.
(6) Keep mud on the cage bottom to prevent the loach from being scratched by the bottom and side walls of the cage, causing skin damage, infection and disease. Prevent and treat diseases in time; before loach are put into cages, disease prevention should be done by soaking and disinfecting with dilute salt water or potassium permanganate solution. In addition, the bleaching powder hanging bag method can also be used, that is, bleaching powder is placed in gauze bags and hung in the cage water area, allowing the bleaching powder to slowly dissolve and diffuse; the principle of multiple points and small amounts can be adopted, hanging bags in the cages for several days.
(7) Pay attention to preventing harm to loach from other organisms, such as snakehead, water snakes, water rats, etc.
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