Development of fish egg & larva can be mainly divided into 6 stages:
1. egg (incubation period)
2. prolarva (yolk sac period)
3. larval (absorbed yolksac but incomplete organ)
4. postlarva (complete organ)
5. juvenil (fry and fingerling)
Larva and fry have some different biological characteristics from adults especially in growth, feeding habit and habitus. During larval stages, the fish have fast growth. They require large amount of quality foods and good environmental conditions.
It is very difficult to determine exactly that how many larvae should be stocked into nursery place. Stocking rate is related to many factors especially foods environmental condition and toleration of each species to the existing conditions. Primary nutrients are required for primary production (phyto and then zooplankton) and maintain it availability in a nursery pond. Phytoplankton level could be correspond to secchi disk visibility. About 35-45 cm secchi disk depth should be keep to maintain a level phytoplankton approximately 80 mg chlorophyl-a/m3).
recapped from A.Choomthi