A Detailed Guide to the Methods and Key Technical Points of Artificial Large Yellow Croaker Farming

I. Grow-out Farming of the Large Yellow Croaker

    For grow-out farming of the large yellow croaker, there are currently two modes, net cages and earthen ponds, both of which have achieved notable results and relatively good economic returns.

    (1) Net-cage Grow-out Farming of the Large Yellow Croaker

    1. Installation and Specifications of the Net Cages

    The installation of net cages during the grow-out stage of the large yellow croaker is basically the same as the requirements during the fingerling rearing stage, except that the cage specifications and mesh size change as the fingerlings grow. The depth of grow-out cages is generally between 3.5-4.0 m, and the mesh size is between 20-60 mm. To avoid injuring the fish by abrasion, it is best to choose knotless netting with a relatively soft texture as the netting material.

    2. Stocking of Fingerlings

    (1) Selection of Fingerlings

    The fingerlings to be stocked should be selected for symmetrical body shape, robust constitution, intact scales on the body surface, and freedom from disease and injury. Fingerlings stocked in the same net cage should be uniform in size. For those intended to reach a marketable size of more than 400 g within the same year, the fingerlings to be stocked should be about 100 g in size.

⟧    (2) Transportation of Fingerlings

    Transportation methods for fingerlings include live-fish boats, live-fish trucks, fish baskets, water tanks, and oxygen-filled plastic bags. For productive long-distance transport in batches, live-fish boat transport is the best. Fingerling transport is generally best carried out in late autumn when the water temperature drops to 18-16 degrees C, or in spring when the water temperature rises above 13 degrees C. Fingerlings must not be transported during disease outbreaks or after being fed to satiation. For live-fish boat transport, choose warm days with little wind. For fingerlings transported by live-fish boat for more than 24 hours, the reference density is 500 fish/m3 (size 75 g), that is, about 40 kg/m3; the density for transport in other water bodies should be much lower than the above.

    (3) Stocking of Fingerlings

    For net cages in sea areas with fast currents, fingerling stocking should be carried out during the neap tide period. After the fingerlings arrive at the cage area, taking advantage of the interval between scooping the fish into buckets and pouring them into the cages, the fingerlings can be soaked and disinfected with a freshwater solution of high-concentration antibiotics and an appropriate amount of formalin. If the fingerlings are transported in a closed water body, sudden changes in conditions such as specific gravity and water temperature should be avoided when transferring them into the cages. This can be done by adding seawater from the cage area to the transport water as a brief transitional treatment. The stocking density of fingerlings is determined according to the water flow conditions inside the cage and the size of the fingerlings. The reference density is about 25 fish/m3 for those of 75 g, and 12-14 fish/m3 before harvest, that is, 6-7 kg/m3.

    3. Feed and Feeding for Net-cage Grow-out