This document discusses the feeding habits of fish. It begins by defining feeding habit as the kind of food an animal habitually consumes during its life or at a particular stage. It then describes different modes of feeding such as herbivores, omnivores, carnivores, and limnivores. The document highlights that understanding the feeding habits of fish is important for polyculture systems. It also discusses the major types of feeding like grazing, predation, straining, sucking, and parasitism. Finally, it provides examples of different mouth structures in fish and how they relate to the fish's diet.