What Do Fish Eat?

Typically a cold blooded organism, fishes are covered with scales. Most of them are found in sea water, while fresh water fishes, and fishes found in streams are also abundantly seen in nature. Fishes have two sets of fins that are paired. They also have smaller unpaired fins. They respire with the help of gills.There are a lot of species of fish living in oceans, rivers and other water bodies. It is difficult to categorize the food which forms the diet of these numerous fishes, yet here is an attempt to make you understand more about their feeding habits.

What Do Fish Eat?
The following classification gives us some idea about the diet of fish.

• Algae: The algae forms the diet of herbivorous as well omnivorous fish. The omnivorous fish eat macroalgaes along with the crustaceans for which they actually hunt.
• Sea Grasses and Algae: The fishes that eat algae and sea grass are totally herbivorous.
• Algae and Detritus: Coral slime, the solid waste matter released from fishes and the organic matter that gets accumulated over time on the sea floor constitutes the detritus. This detritus forms the diet of many fishes.
• Sponges: Omnivorous fishes like the Angel fish feed on sponges. The sponges form a bulk of their diet.
• Plankton: The plankton which includes different types of fishes, shrimps, copepods, mysids and amphipods forms a supplementary part of the diet of fish.
• Fishes Feeding at the Ocean Bottom: Fishes that come under this category are omnivorous. They are opportunistic in nature and survive on any kind of food they get near the bottom of the sea. Their diet includes worms, small fishes, crustaceans and almost everything that is edible.
• Fish Feeders: The fishes that eat other fishes by means of ambush come under this category.
• Crustacean Feeders: Shrimps and crabs form the major diet of these fishes.
• Generalized Invertebrate Feeders: Small invertebrates that form the diet of these fishes are snails, sea urchins, worms and star fishes. The sedentary or sessile organisms like the coral polyps and clams too form the diet of these invertebrate feeders.
• Parasite Pickers: Sometimes fishes also feed on parasite of other fishes.

After the generalized classification of the diet of fish, it would be interesting to know about the specific diet of different fishes.

• Sharks: The sharks feed on seals, smaller fishes, plankton available in the sea and also their own species.
• Dolphins: Feeding on a variety of fishes, the major diet of dolphins include squids and mackerels. Mackerels are preferred by dolphins over the squids as mackerels contain large amount of fats. They also feed on cods, herrings and plankton.
• Salmon: The salmons are carnivores and feed on small invertebrates and zoo plankton when they are younger. As they get bigger in size, the salmons start eating krills, herrings and other small fishes. The salmons reared in farms are fed with mixture of different types of fish.
• Jelly Fish: The jelly fish doesn't have a developed digestive system. They eat the food that gets attached to their tentacles. Generally, zoo plankton and small fishes form the diet of the jelly fish.
• Scorpion Fish: This fish makes use of the ambush technique and preys on smaller fishes.
• Gold Fish: The gold fish is omnivorous and its diet ranges from plankton, detritus, worms, insects to larvae.
• Koi fish: The koi fish feeds on lettuce, algae and peas. The koi fish in aquariums are not fed with a high protein diet, as it causes digestive problems.

The diet of fishes is influenced by the environment in which they live. Most of the fishes are carnivorous, while a few of them are completely herbivorous. Finally we can say that, fishes obtain rich nutrients from the sea environment, in which they inhabit.