The larvae emerging from the fertilized eggs after hatching is called hatchling. It is characterized by the presence of yolk sac hanging below from where it draws its nutrition for 2–3 days. At this stage the mouth is not formed and hence it does not take food from outside.
As soon as the yolk sac of the hatchling is absorbed it is known as spawn. At this stage the mouth is formed and it starts taking small zooplankton like rotifers and supplementary feed like egg yolk, finely powdered oil cake, rice bran etc.
As soon as the spawn assume the shape of the fish and grow to about 1–2 cm it is known as fry. At this stage they are primarily smaller size zooplankton feeder. It takes about 7 to 10 days for the spawn to grow up to fry stage.
As soon as the fry grow up to 10–15 cm size or roughly equal the size of a finger it is known as fingerling. Fingerling is the proper size for stocking in table fish production ponds. It takes about 30–60 days for the fry to grow up to fingerling size.