No, in general most fry and fingerlings can be reared quite successfully on ordinary crumbles and small pellets, if specifically designed for trout, carp or catfish, combined with some natural foods where possible (like green water full of phytoplankton).

Specialist diets are generally only used for higher-value fry like ornamentals or for mono-sex tilapia production.

Juvenile catfish Clarias gariepinus require a yeast-based artificial diet to achieve high survival and even growth.