Do Catfish Have Scales? Why Do Catfish Have Such Slimy Skin?

Named after the pairs of cat-like whiskers on their head, catfish are a diverse group of fish belonging to the Ictaluridae family.

Besides their prominent whiskers, one of the catfish's other striking features is their lack of scales on their bodies. Scales on a fish's body have a lot of uses, ranging from aiding in protection to helping them swim through the water easily by reducing friction.

Though catfish do not have scales to protect them, they do have a thick coating of mucus, which keeps external threats among the ocean like parasites and deadly bacteria away. A few catfish species also have bony plates called scutes, which offer an extra layer of protection instead of scales.

However, the most well-known catfish species like the channel catfish and flathead catfish have smooth, leathery skin.

As an added measure for protection, catfish also have three spines present on their backs, which help to deter any predators. To learn more about these fabulous fish, read on!

If you enjoy this article, you can find more interesting facts on our how long catfish live and when catfish spawn pages.

Why do fish have scales?

Many fish are covered with small, hard plates made from collagen and calcium, which grow out of their skin. These are known as scales.

Scales have a number of benefits that help fish when it comes to survival and mobility both. The size and appearance of scales differ from species to species, with fish like carp having huge scales, whereas rays have scales that are almost invisible.

Scales differ in texture and appearance as well, with many species of fish having smooth, rounded scales, whereas others have scales with sharp, serrated edges.

Scales are not only for appearances and are actually a form of body armor for fish-providing them some level of protection from predators. Scales cover the body of the fish in an overlapping pattern, so as not to allow any parasites to slip through, or let any obstructions in the water cause injury to their soft body beneath.

Though scales are an important factor in keeping fish safe, they are not exactly the final layer of defense - the actual last layer of protection being a generous layer of mucus on the scales.

Scales also help fish glide gracefully through the water. Fish are streamlined in shape, which helps them to cut through the water easily, they use their fins and tail to push water back and forth, helping them to move through.

Scales help to make swimming for fish easier, by reducing the friction between the water and the body of the fish. It also makes fish more water-resistant, helping them slice through the water without much difficulty.

Many fish also have scales that have special properties, helping them to confuse predators or aid their escape. Many fish species have colorful scales, which help them to blend in with their surroundings or confuse predators by swimming around in schools and flashing their bright colors at them.

Others have reflective scales, which bounce light back at larger enemies like sharks and sea snakes, causing momentary blindness which can help them to swim away.

Why do catfish have skin and not scales?

Though fish are known for their presence of scales, catfish are a type of fish that do not possess this main identifying feature! Unlike other fish, it is very likely that catfish simply entered the world that way, and just evolved differently to possess leathery, slippery skin for protection rather than tough scales.

Though some catfish have bony plates called scutes, most catfish species appear naked, with scaleless skin.

There are 39 known species of catfish on this planet, and none of them possess scales!

Though all of them have spiny fins which aid in protection and cause discomfort, and a few species do possess scutes, there is not a single scale to be seen on any catfish in the world. Maybe they did have scales long ago, and they simply evolved to become scaleless over the years.

Though the reason is unknown, the fact of the matter is that catfish having scaleless skin does make them more recognizable!

It is theorized that the lack of scales helps catfish to breathe better, allowing the oxygen to be taken in from the water through their slippery skin. Though catfish do have gills, the extra surface area helps to take in more oxygen and helps them to breathe easily.

Does a catfish's leathery skin make it harder to clean?

Typical catfish species like flathead catfish, bullhead catfish, and channel catfish are actually very very good in taste and are considered a delicacy in many parts of the world.

Though many people eat fish with the skin on them after descaling them, this is not the case with catfish. As most species of catfish have tough, scaly skin, they are meant to be eaten without the outer covering.

That being said, it is quite difficult to take the skin off of raw catfish.

If you are planning to eat catfish, it is recommended to thoroughly wash all the mucus off its body, before scoring its skin and cooking it.

Not scoring the skin before cooking causes it to curl up, making it difficult to remove. Once it is properly cooked, the skin will peel right off, after which you can eat the catfish with ease and enjoy its sweet, mild taste!

It is recommended to soak catfish in milk for a couple of hours before cooking it, as this will make it moist and flakey as well as remove any fishy odor and taste, giving it a very pleasant flavor and texture.

You need not worry about cleaning the skin properly, as catfish are meant to be eaten without the skin. Even if it's cooked, the skin remains tough and leathery, giving it a very unpleasant texture that can ruin the taste.

Why don't catfish have scales?

There is no concrete explanation for why catfish do not have scales, they simply appear to have evolved that way. Their smooth, mucus-covered skin likely helps them to breathe easier, helping to take in oxygen from the water through the skin.

Though many catfish species are naked, a number of them, such as the Callichthyidae, do have bony armor plates called scutes, which help to offer them some level of protection.

The most common catfish species, like the flathead catfish, bullhead catfish, and channel catfish have the typical leathery, slippery skin associated with catfish.

Though they do not have scales, the thick layer of mucus covering their bodies does provide a certain layer of protection, keeping away parasites and other disease-causing bacteria from attacking their skin or entering their bodies through their gills.

They also have four pairs of whisker-like organs called barbels present on their head, which help them to detect food and other obstacles in the murky water.

These cat-like whiskers are what give catfish their name.

An interesting mechanism that many catfish species possess is their pectoral fins, with which they create vibrations and send them through the water to produce sounds. These can act as signals in times of danger.

They also have outward-facing external pectoral fins, which can act as a defense mechanism, which are called spines. The dorsal fin also has two spines, making a total of three spines. The presence of a bony spine makes it more difficult for predators to swallow them.

Catfish usually do not pose any threat to humans, though there are some species that possess stings embedded behind their pairs of fins (mostly non-venomous in nature), which they can use to pierce through the skin of any intruders if they feel threatened.

However, there are cases in which catfish have killed humans with a toxic bite, like the striped eel catfish.

What aquarium fish don't have scales?

Besides catfish, there do exist a number of fish species that do not possess scales either. Though most catfish are naked and have smooth, slippery skin, there are a few catfish species that possess tough, bony body armor to protect themselves from predators.

Clingfish are small aquarium fishes that have smooth, scaleless skin - similar to that of catfish. They are called clingfish due to the presence of a circular 'sucking disc' on their undersides, which they use to attach themselves firmly to various surfaces, which helps to keep them stable in times of rough water currents.

They are fairly popular in the aquarium trade.

Eels are another type of fish that don't have scales. Though they seem to have smooth, slippery skin, eels actually do have minuscule scales, which are embedded in their skin.

One of the beliefs as to why their scales are so tiny is that to co-ordinate with their long, flexible bodies, their scales evolved to be tiny as to not get in the way when they hook onto things.

Hence, their skin appears smooth and scaleless. The dorsal fin and anal fin of eels are also joined together, forming a single unit.

Similar to eels, sharks also seem to have smooth, leathery skin but are in fact covered with minuscule scales. Sharks are actually covered in thousands of tiny scales called dermal denticles.

These tiny teeth-like scales point towards the tail end of the shark and help reduce friction between the water and the shark while it is swimming. Rays and skates have similar, sandpaper-like skin to that of sharks.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for whether catfish have scales then why not take a look at what catfish eat, or catfish facts.