If the fish do not spawn in the spawning tank, especially those newly caught from the wild during the spawning season, the eggs and milt can be stripped and fertilized artificially. In this case, the readiness of spawners has to be checked before stripping. If the eggs are in the running stage, there is no need to inject hormones. If the eggs are not at the running stage, they will have to be induced by hormone injection.
The healthy ripe running eggs have the following characteristics:
The stripping can be done as follows:
Collect the milt first and keep in a dry test tube. Seal the top and keep at 4°–8°C. If the milt is well prepared, it can be kept for five days. Strip the eggs from the female into a dry clean tray; stir the milt thoroughly with a feather. To facilitate mixing, seawater with a salinity of about 28–30 ppt is added to cover all the eggs. Continue stirring the eggs for a further 1–3 minutes. Through the strain, wash the eggs with seawater 3 or 4 times to remove mucus and foreign substances which could cause subsequent bacterial infection. Fertilization takes place in about three minutes, after which the eggs must be placed in a hatching container.
