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What Do Fish Eat in the Wild and as Pets?

Nicole Cosgrove

The aquatic world is both fascinating and mysterious. We know so little about our ocean friends that no question is a dumb one. So, what do fish eat in the wild?

Fish are cold-blooded creatures that are found all over the world. A variety of different types of fish live in fresh and saltwater, from small minnows to giant sharks. What they eat can depend on a number of factors such as their size, location, and availability. There is no one “perfect” diet for a fish because some species will consume both plants or animals while others only eat one type!

Now that humans have domesticated them, it could be important to know more about their diet. This blog post will explore the different types of fish, what they eat in the wild, and as pets.

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Carnivorous Fish

shark eating fish
Image Credit: Richard Condlyffe, Shutterstock

As stated earlier, we can split fish-eating habits into three categories. The first category includes carnivores, meaning they only eat meat. These fish are fast swimmers and will typically avoid anything that is not moving or struggling.

Carnivorous fish can either be freshwater or saltwater, but some prefer one environment to the other. The rule of “big fish eats smaller fish” is in full effect here, as predatory fish will typically eat anything smaller than themselves.

Saltwater carnivorous fish eat things like squid, small tuna, and other smaller fish; freshwater carnivores will typically eat smaller species of trout, salmon, or catfish. Salmon is also known to feed on herring, while giant bluefin tuna have been seen eating dolphins!

The most well-known example of a predatory fish is definitely the Great White shark. Great White sharks are ferocious predators and have been known to eat whales, seals, sea lions, penguins, and pretty much anything else that they can get their jaws on.

They can smell blood in the water from miles away and will chase their prey at high speeds. Once they have the animal within range, they’ll use a technique called “bouncing,” in which they swim up out of the water to attack from above before swimming back down below its victim for an easy kill.

Carnivorous fish can also be divided into two groups: ambush predators and pursuit predators. Ambush predators typically wait until something comes close enough that is worth eating before attacking; these include piranhas and pike-fish! Pursuit predators are more active hunters who actively hunt their prey by using speed or camouflage techniques such as changing colors to match the backdrop of their environment.”

Many carnivorous fishes will also be considered an omnivore if they occasionally feed on plants or other animals as well as insects (insects are often eaten whole). The most famous examples include Oscars, Angel Fish, and Siamese Fighting Fish, which both enjoy munching down leaves!

Herbivorous Fish

albino cory catfish
Image: Pxfuel

Herbivores are generally slower swimmers and will typically only eat plants, such as seaweed or algae. Some of these fish include freshwater species like African catfish, Nile perch, tilapia, trout (freshwater), and carp; herbivorous saltwater fish include sardines and anchovies.

Herbivores are also more likely to be found in the shallows, where they can find enough vegetation. This is because they get their nutrients from the plants they eat and the waters they live in.

It’s important to note that herbivore fish are not restricted to eating plants; some will also eat small invertebrates like crustaceans and insects, such as Black bass do. The appetite of herbivore fish is often controlled by the availability of food in their environment, so they won’t always be hungry if there’s plenty around.

Herbivores have a lower chance of being bitten by predatory species because they don’t move at high speeds or swim into deep water. A predator would need luck for both conditions to happen simultaneously!

Omnivorous Fish

bass_fish_pixabay
Image Credit: Pixabay

Omnivores also enjoy munching down on leaves (as well as insects), but this time the most famous examples include bass, which loved catching bugs before it was domesticated! This type has teeth that can tear meat like nothing, so small fish are also on the menu.

Omnivorous fish will eat anything that they can find because their stomachs have the capability to digest a variety of food sources. Omnivores spend most of their lives near the surface, so they can find more food.

In the ocean, omnivorous creatures are probably the most abundant, though we do not know what else is lurking in the abyss.divider-fishbowl

Pet Fish

surgeon fish
Image Credit: susanne906, Pixabay

The majority of pet fish you will find in pet stores are herbivores, which means they mostly eat plants. Feeding them will be a breeze since their food is premade for you.

Pet fish are the same as wild ones in that they have teeth, but these are more like molars for grinding food and not tearing it apart (like carnivorous fish).

Pet fish tend to be a little bit smaller than their wild counterparts of other types, although there are exceptions, so always double-check before you buy a fish if tank size matters to you.

Carnivorous Pet Fish

piranhas swimming
Image Credit: AllNikArt, Pixabay

Carnivorous pet fish are becoming more popular in the aquarium hobby because their teeth are designed like those of a shark (for tearing flesh)! The most popular carnivore pet fish is the piranha. That’s not a fish to get if you are squeamish!

Feeding piranhas involves either a live fish or a chunk of meat as the piranha will kill and eat either.

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There are many different types of fish. Depending on the type, they have a specific diet that will vary greatly from one to another. Fish can be classified as omnivorous (eating both plants and animals), carnivorous (only eating meat), or herbivore (only consuming plant material).

Wild fish and domestic fish also share some similarities in their basic dietary needs depending on their category. If you want to know more about the mysterious aquatic world, check out the rest of our blog for all your fish-related questions!


Featured Image Credit: Pexels, Pixabay

Nicole Cosgrove

Nicole is the proud mom of Baby, a Burmese cat and Rosa, a New Zealand Huntaway. A Canadian expat, Nicole now lives on a lush forest property with her Kiwi husband in New Zealand. She has a strong love for all animals of all shapes and sizes (and particularly loves a good interspecies friendship) and wants to share her animal knowledge and other experts' knowledge with pet lovers across the globe.