The growth rate and fatness of fish depend upon the amount of food available and its nutritive value. Different fishes feed on different foods. For instance, grass carp feed on various aquatic and terrestrial plants, black roach feed on snails, white bighead feed on phytoplankton, striped bighead feed on zooplankton, and carp and goldfish are omnivorous. Generally, fish can be grouped into carnivores, herbivores, and omnivores. However, during young stages, most fish feed on plankton.