What Do Catfish Eat?

Catfish eat a wide range of plants and animals but primarily eat insects, water beetles, small fish, plants, algae, crawfish, snails, and just about anything else they can manage to fit in their mouths. Most catfish are not picky eaters and are scavengers, meaning they are happy to eat just about anything.

Our diet is widely varied and includes many things that range from exotic meats, for the adventurous, to common plants and vegetables. This is because we are an omnivorous species capable of eating, ensuring that starving is kept at a minimum.

In the world, there are many species whose diet are similar to ours and others whose diet are widely different. There are species of bacteria capable of eating plastic, a potential solution to the world’s plastic overdose. There are species of beetles that are used in museums because they eat the entire flesh off of bones, which is a great way to clean skeletons for scientists. There are even crocodiles that eat stone because it helps them to submerge. Catfishes are a large group of fish that have a wide variety of diet throughout the many species that make up the group. They range from the normal and obvious to the weird and extreme.

Representation of a Mekong giant catfish at a Buddhist temple in Chiang Khong. Image from Wikipedia

What Are Catfish?

Catfish belongs to the order Siluriformes, which is composed of ray-finned fish. They exist in wide ranges of sizes, behaviors, regions, and even diet. Catfish have existed on all the continents at some point in time and today they can be found on all of them except for Antarctica. They are most prominent in South America and over 50% of all catfish species can be found in the Americas. Majority of the species are freshwater fish and found in places like rivers, lakes, and ponds. There are species that are also found in caves and underground. There are also a few species that are found in salt water, though these are rare.

Catfish are named because of their distinct whisker-like barbels, which are a sensory organ that contains taste buds and used to detect food in the surrounding environment. Most catfish are bottom feeders and generally sink rather than float because of their dense bones and reduced gases in their body. They do not have scales and about 50% of catfish species are sexually dimorphic.

Catfish are important to humans because they act as a food source. They are easy to grow and raise, which reduces the cost of taking care of them. Channel catfish accounts for over $400 million a year in revenue for the United States and is one of the most populous catfish species in North America. Catfish have been used as a food source for hundreds of years across the world through many different cultures and regions.

What Do They Eat?

Because of catfish range from different sizes, habitats, and features, they also have a range of diets. Their diet also changes as they age. Like humans, most catfish are omnivorous and generally eat things like other fish, aquatic plants, and invertebrates. There are a few catfish that go outside of this common diet. Some species eat things like wood and algae while there are other parasitic species that consume the blood of other fish and have developed horrid tales about themselves. There are even species of catfish that engage in cannibalistic behaviors.

The Panaque

The panaque is a genus of catfish that includes species capable of digesting wood as part of their diet. This is a practice known as xylophagy. All the species in this genus comes from South America and lives in streams and rivers. To survive in these environments, these catfish have tough armored skins and strong suckers to hold onto rocks. They are omnivorous and eat things like algae. Scientists believe that they eat wood because they have scraper-like teeth and highly angled jaws, both of which indicate consumption of wood. They also have gut bacteria that is capable of breaking down cellulose, the main component in wood, and providing digestible material to the host catfish.

Panaque nigrolineatus in an aquarium. image from Wikipedia/Neale Monks

The Mekong Catfish

The Mekong catfish is a critically endangered species of shark catfish found in Southeast Asia and represents one of the largest species of catfish in the world. Verified records have one Mekong catfish at 2.7m and other records indicate that this species can achieve a weight of 770lb. Despite their large size and reference as a shark catfish, they mostly eat algae. When they are young they generally eat zooplankton and engage in cannibalistic behaviors. After they become one year old, their diet changes from carnivorous to herbivorous and eat only algae. They consume large amounts of algae in order to grow bigger and sustain their sizes. This species has lost over 80% of its natural habitat and that has driven it to become critically endangered. This lack of habitat makes it harder for the species to consume the necessary amounts of food it needs and they simply cannot sustain themselves or their species.

The Candiru

Candiru, Vandellia cirrhosa, is a species of catfish that is parasitic that is located in the Amazon Basin. They are typically small with an average size of 7 inches. These parasites attach themselves to the gills of larger fish and feed on their blood. The relationship is one-sided as the candiru benefits from it and the host fish is left in misery. This species remained insignificant and unknown to most people but at a certain point, it began to develop a rather unfortunate story around it. Based on many graphic anecdotes, the majority of which are unverified and any others are viewed with great suspicion, the candiru has developed a reputation of attaching itself to the urethra of males, forming a terrible relationship. These stories started in the 19th century and continue today with the infamous tale of the candiru traveling up the urine stream to the urethra, which is fake because simple physics does allow for such actions. There is no scientific evidence to support any of these claims and they are all probably misconceptions or lies.

There are many other species of catfish that we have yet to fully understand and probably much more that we have not even discovered yet. As we continue to explore the deep waters of the Earth, we will hopefully continue to find more different and interesting species to help us understand the diversity of the world we live in.

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