Best Catfish For Koi Pond

People who keep fish in aquariums know that certain species, like catfish, are helpful because they keep the environment clean by consuming food debris, algae, and waste material in the tank. What works for an aquarium should also work in principle for koi ponds, right? Well, unfortunately, it’s not that simple. So what is the best catfish for a koi pond?

The best catfish for a koi pond is from the Plecostomus family, such as the common pleco. However, you should always ensure that they are roughly the same size as the koi to prevent them from eating or hurting them. Other types of catfish compete with koi for food as they consume the same things but can grow much faster.

The best catfish for a koi pond is:

  • Common Plecos, also known as suckermouth catfish
  • Adonis Pleco
  • Golden Nugget Pleco

Catfish are bottom feeders like koi. Koi bred in captivity have learned to eat food from the water’s surface, but they will still scrounge for food at the bottom of the pond. This is their natural behavior in the wild. This article looks at whether you can keep catfish in a pond, which kind of catfish is best, which type of catfish you should not put in your pond, and more!.

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Best Catfish For A Koi Pond

To understand more about keeping catfish in a koi pond, we need to give them a closer look. There’s a wide variety of catfish with some, like the channel catfish, that can grow to forty pounds in weight! Some catfish grow big enough to swallow birds and other small animals, while others stay much smaller.

The best catfish for a koi pond is Plecos, short for Plecostomus. Plecos are the suckerfish commonly kept in aquariums, but they can live in a koi pond if the water is kept warm enough. They come in various kinds and sizes and can live for twenty to thirty years.

Common Pleco

Common Plecos are also known as a suckermouth catfish

The Common pleco, Hypostomus Plecostomus, is much prized for aquariums and can often be seen latched onto the glass walls sucking off the algae. Plecos originate from South America and are fondly called fish janitors.

Many Plecos can help keep a koi pond free of algae, but they are not cold tolerant, so you may have to overwinter them indoors in an aquarium. The common pleco is inexpensive and can grow up to two feet in length. They eat feces, dead fish, and algae, so they are helpful in koi ponds.

Plecos are known for getting along with koi, but you would need to choose one of a suitable size for your pond and your koi. There is a risk that your koi could eat a Pleco, but it is slight if they are well fed. There is a risk that a large Pleco could suck in a small koi as it feeds, but it isn’t usually a serious problem.

If you keep catfish that grow larger than the koi, you will at some stage have to remove the catfish from the pond or risk your koi being eaten. Koi also eat algae, so you don’t want too many catfish competing with the koi for this food source.

Adonis Pleco

Adonis pleco

The Adonis Pleco can be pretty aggressive, so it may not be a good choice for a koi pond with smaller koi in it.

The Golden Nugget Pleco

Golden Nugget pleco

The Golden nugget Plecos can also live amicably with koi. An important thing is to make sure that the fish are all of a similar size.

How Many Catfish Should I Put In My Koi Pond?

If you keep catfish in your koi pond, you should probably have only one. Some koi keepers report keeping a single catfish with no trouble. Others point out that while koi and catfish may live in harmony for a while, the larger types of catfish will outgrow the koi and could eventually kill or injure them. It’s best if the catfish and the koi are more or less the same size.

Koi can also bully smaller fish; most koi keepers say you shouldn’t keep any other fish with them. A large catfish may also try to corral the koi at one end of the pond, stressing them out.

What Catfish Should I Not Put In My Koi Pond

If the catfish is bigger than your koi, the chances are also good that you’ll wake up one morning to fewer koi in your pond. Just as koi eat smaller fish and even their fry, so will a catfish. The catfish will eat the koi eggs too, and they quickly learn to come when it’s feeding time.

Channel Cat

Channel catfish

One of the most popular catfish in America is Ictalurus punctatus or the channel cat. This fish is highly adaptable to various conditions and is most commonly sold to pond owners in the US. However, channel cats are not ideal for koi ponds because they grow too fast and get too big.

The channel cat is often sold for aquaculture purposes and is keenly hunted by fishermen because it is the tastiest catfish. It occurs in large numbers in the US in the wild, which tells you that it is a hardy, dominant survivor that successfully competes with other fish. If you decide to keep one in your koi pond, you will probably have to remove it once it outgrows the koi.

The channel cat has spines on its dorsal and pectoral fins. Some koi keepers have said that these spines rip into their koi, causing severe injuries, and they will never keep these catfish again. Catfish can be aggressive and may bully the koi as they are not too social.

You may be better off with a Pond Loach, Misgurnus anguillicaudatus, than a channel catfish in your koi pond. The loach is known to live peaceably with koi. Because they are bottom feeders, catfish can stir up the sediment in a koi pond and turn it cloudy. Channel catfish are nocturnal, which may also cause stress to sleeping koi.

Wels Catfish

Wels Catfish

The Wels catfish, Silurus glanis, is the largest freshwater fish in Europe, growing up to eight feet long and weighing up to six hundred and seventy-four pounds in warmer waters. They feed on small mammals, other fish, and waterfowl. You don’t want a monster of this size in your koi pond.

Small Catfish Might Get Eaten By Large Koi Fish

A flock of glass catfish in an aquarium

Small catfish species such as the glass catfish, bristlenose catfish, and cory catfish only reach a length of around 2.3 inches, so there is a risk that your larger koi could see it as a fishy snack if they are still hungry.

Bristlenose pleco
Cory catfish

Can Catfish Eat Koi Food

Koi fish eating pellets

Catfish are also omnivores – like koi. In their natural environment, they will eat decomposing animals, dead fish, algae, worms, shrimp, frogs, insects, seeds, larvae, and other smaller fish.

Catfish eat huge quantities and grow very fast compared to koi. They are therefore competitors for koi. Since koi food is usually expensive, you don’t want a giant catfish muscling the koi out of the way to guzzle it down at every feeding. If you put too many of them in a koi pond, you could end up with large food bills and hungry, slow-growing, stunted koi.

Can I Put A Wild-Caught Catfish In My Koi Pond?

Wild-caught catfish carry diseases and parasites that can spread to the koi, so dumping a couple of them in your koi pond after a fishing trip is the worst thing you can do. While catfish come with some advantages, they also come with disadvantages, and many serious koi hobbyists will not add them to their ponds because the risks are too high.

Do Catfish Produce Loads Of Waste?

The size to which a catfish can grow is a material consideration when considering one for a koi pond because catfish also poop alot, contributing to the fish waste in the water. Big fish produce a lot of poop which doesn’t help keep your koi pond clean.


The best catfish to keep in a koi pond are those from the Plectostomus family, but you will need to keep the water warmer or may have to overwinter them in an aquarium because they are not cold tolerant. Most koi keepers don’t recommend keeping catfish in a koi pond because the benefits do not outweigh the disadvantages.


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