We examined the relationship between the intestine length and the amount of plant material in the diet of 21 species of fish from forest streams in Panama. Alimentary tract analyses supplemented by literature reports showed that four loricariid catfish species and one poeciliid were specialized herbivores consuming almost exclusively periphyton and detritus. Four species, including one erythrinid, one characid, one trichomyctycterid and one eleotrid, were carnivores consuming almost entirely food of animal origin. Twelve species, including five characids, one lebiasinid, two pimelodelids, three cichlids and one poeciliid, were omnivores consuming food of both plant and animal origin, but the average proportion of food of plant origin (detritus and algae plus higher plant parts) varied from 4–60%. Most omnivores increased plant food consumption with increasing size. Because intestine length increases allometrically with body size and the pattern of increase differs considerably among species and is influenced by length:mass relationships, we compared species at the same size and took both length and mass into account. At a given size, intestine lengths of herbivores were longer than those of omnivores, and these were longer than those of carnivores. Differences in intestine length among the dietary categories were greater at larger body sizes and when the common size was defined by body mass than when it was defined by body length. There was no trend for the average proportion of plant material consumed to be related to intestine length among the omnivores, when confounding effects of body mass were taken into account. The slopes of the allometric equations relating log10 intestine length to log10 body size for herbivores tended to be higher than for omnivores and higher for omnivores than for carnivores, but both herbivores and omnivores showed extensive variation and overlap with the other dietary categories. Among the omnivores, there was no trend for slopes to be steeper for species consuming more plant material on average or for species showing larger ontogenetic increases in plant consumption. These results permit increased precision in describing diet-intestine length relationships, but indicate that the widely held belief that intestine length reflects diet in fishes should only be applied to broad dietary categories and not to finer divisions among omnivores.
, , and are members of the order, but they are omnivores.
Most of the black bear's diet consists of plants. In the summer months it eats grasses, herbs, sedges, fruits, berries, and nuts. It also eats . Black bears don't hunt for meat, but if they happen to come across carrion (a dead animal) they will eat it.
The brown bear eats berries, roots, fungi, grasses, fish, carrion, small mammals, and insects. Unlike the black bear, the brown bear is a hunter. It is very good at catching fish and often uses its long claws to dig insects out of rotting logs and small mammals out of their burrows. Some brown bears in the Canadian Rockies hunt larger animals like , elk, and goats.
The primary food source for the polar bear is seals. It also eats fish, seabirds, and sometimes, . In the summer, it also eats berries and other plant parts.
Omnivore Spirulina Crumble Bits 2-4mm - Spirulina Fish Food
Although the native catfish habitat varies drastically, all catfish love to eat, and despite popular belief, they are not all bottom-feeders. Catfish travel where the food is, whether that’s shuffling along on a riverbed or skimming the water’s surface looking for larger prey. Wild catfish have very diverse feeding behaviors, with some remaining strict scavengers and others preferring to swallow large fish and other prey whole. Some can be carnivores, herbivores, omnivores, or even limnivores (eating microorganisms within mud).
The majority of aquarium fish are omnivores
Tangs and Surgeonfish are omnivores, but a large part of their diet consists of algae and plant matter. Some tangs, especially the "Bristletooth Tangs" from the genus, can help control nuisance algae in the aquarium, and you will often see them browsing on rock and other surfaces for algae growing there. It is important to feed these fish a varied omnivore or herbivore diet to keep them healthy and looking their best. You may also choose to supplement food items with a multivitamin soak(A, D, E, B complex, and Iodine). Tangs that are fed high protein, meaty foods over a long period of time are more likely to suffer from head and lateral line erosion (HLLE). HLLE disease not initially fatal, but will lead to an eventual decline in the health of your fish if their dietary needs are not met.
Authentic Chinese Steamed Fish | Omnivore's Cookbook