Breeding Techniques and Precautions for Snake-Shaped Eels
Eel refers to the general term for species classified under the order Anguilliformes. Also known as rice field eel, it is a fish with an appearance similar to a long snake shape, possessing the basic characteristics of fish. In addition, eels, similar to salmon, have migratory characteristics. Eels belong to the fish family, resemble snakes, but have no scales, and are generally found in the sea areas where saltwater and freshwater meet.
In recent years, the price of eels has continued to rise and has now reached a stable state. Eel is one of the highly profitable aquaculture species. The specific breeding techniques and precautions are as follows:
I. Water Quality Environment
It is advisable to choose a sea area near an estuary with an open water surface, good water quality, low wind speed, and a water depth that can be maintained at more than 4 m at low tide for setting up cages. The water temperature range should be 8°C-30°C, the sea current speed should be below 1 m/s, and a water area with a flow speed of 0.5 m/s is best.
II. Cage Specifications
For seawater eel farming, it is advisable to use seamless mesh cages of 3 m×3 m×3 m or 6 m×3 m×3 m. The mesh specifications are: 0.5 cm for raising black fry eels and young eels, and 0.8 cm for raising adult eels. Place a 1 m×0.5 m×1 m multi-layer net rack inside the cage as a resting platform for the eels. Leave an open 15 cm anti-escape net brim on the cage to prevent the eels from escaping when the water is turbulent.
III. Fry Stocking
For stocking eels, young eels are best, with a stocking density of 150 tails per sq m. If there are no young eels and black fry eels are stocked instead, the density is 500 tails per sq m. Before stocking, the eel fry should first be disinfected with a medicated bath to prevent disease.
IV. Feeding Management
a. Water Quality Management
Water quality management in eel farming is particularly important. The seawater specific gravity is required to be 1.01-1.02, dissolved oxygen should be more than 5 mg per liter, and the pH value should be 7-8.5. In recent years, some aquaculture farms have used the microbial preparation EM Original Dew produced through China-Japan cooperation to regulate water quality, soak and mix feed, and prevent fish diseases, achieving successful experience and good economic benefits.
b. Feed Feeding
Feeding eels should follow the “four fixed” principles. That is, fixed time: except in early spring and winter when feed is given once at 8 PM every day, at other times feed is given once each at 5 AM and 8 PM every day; fixed location: feed on fixed feeding platforms; fixed quality: feed a complete formula feed supplemented with special multivitamins for eels; fixed quantity: the total daily ration is calculated as a percentage of the total body weight of the eels, 15% during the adult eel stage, 3% during the young eel stage, about 5% during the black fry eel stage, and 0.5%-1% during high-temperature and overwintering periods.
c. Timely Cage Separation
After about one month of rearing, the density of eels increases greatly and individual differences become more pronounced. They must be screened and separated into cages in a timely manner, separated according to physical strength and individual size. During the screening and cage separation process, operations should be careful and meticulous to avoid scratching the fish bodies, prevent infection, and carry out medicated bath disinfection.
d. Replacing Cages
To keep the cages clean and hygienic, prevent disease, and ensure unobstructed water exchange, the cages should be replaced in a timely manner. Replace once every 10 days in summer and autumn, and once every 50 days in early spring and winter. The replaced nets should be cleaned immediately for next use.
e. Daily Management
Implement group management of the cages. Test water quality every day, and keep detailed records of weather, water temperature, pH value, feeding, disease prevention and treatment, etc. Observe the feeding and growth of the eels, and deal with problems promptly when found.