A number of generalizations about the gut of fishes have been attempted, many of them extrapolated from terrestrial vertebrates. The commonest of these, the observation that herbivores have longer guts than carnivores, appears only partially true in fish. While this may be true in limited groups of fish, it is not universal in teleosts as a whole. Gut lengths have been listed as 0.2-2.5, 0.6-8.0 and 0.8-15.0 times body length in carnivores, omnivores, and herbivores, respectively. Thus, the longest guts are found in herbivores, but not all herbivores have long guts; i.e., the gut lengths of some herbivores are shorter than those of some carnivores. Part of the explanation lies in the fact that many fish eat a variety of food, sometimes ingested with considerable indigestible material (e.g. mud) which often influences gut length. The size of the food particles - from submicroscopic plankton to whole fish - may also influence gut configuration.