I enjoy keeping both saltwater and freshwater fish tanks and sharing my knowledge with other aquarists.
When you begin to populate your freshwater aquarium, it will most likely be necessary to include some bottom feeders, scavengers, and algae eaters. With nine classes and hundreds of individual varieties, freshwater catfish can fill all of these needs. To help you understand which catfish are right for your tank, consult the guide below.
- Armored Catfish
- Armored Sucker Mouthed Catfish (Plecos and Otos)
- Air Breathers (Walking Catfish)
- Banjo Catfish
- Talking Catfish (Rafael)
- Upside Down Catfish (Synodontis)
- Sheatfish (Glass or Ghost Catfish)
- Long Whiskered Catfish (Pictus Catfish)
Among the most common freshwater catfish are corydoras (Greek for “helmet skin”), a small armored variety that commons in several variations. Corydoras, or Corys as they are often called, range from 1 to 4 inches long and spend their time scurrying around the bottom of the tank cleaning up excess flake food and various other debris. They have a scaly armor plating that protects them from predatory fish so they can be kept with most semi-aggressive fish and highly aggressive fish that are not much larger than 2 inches (bumblebee puffers, for example).
Corys are extremely peaceful and will get along with almost any other community fish. They can be kept in schools or individually, and it is perfectly acceptable to mix varieties in the same aquarium as there is no territorial aggression with like species. This is part of the reason they are perfect bottom dwellers for a beginner tank.
Cory cats feed by foraging for loose vegetation, algae, insect larvae, and worms. Although they will not attack or eat live or sickly fish, they will scavenge carcasses. They forage by using their sensory barbs on the tank bed, often burying themselves up to their eyeballs. For this reason, they should have a fine sandy substrate to eliminate any chance of injury.
Cory cats are not nocturnal like most other catfish. This makes them a great addition to a tank that is viewed primarily in the daytime. They are active and peaceful but a bit skittish at the same time. Make sure to provide several hiding places for these little guys so they don’t stress themselves out.
Armored Sucker Mouthed Catfish
Armored sucker mouthed catfish come into two general subclasses: Plecostomus (Plecos) and Otocinclus (Otos).
Plecos are usually sold in pet shops very early in their lives, when they are still between 3 and 5 inches long. An adult Pleco can grow to as large as 2 feet (but may take up to 20 years to do so). They are semi-aggressive, bottom-feeding omnivores.
They prefer to graze on plants and algae and usually do so at night. If there isn’t enough food for the Pleco, between foraging plants and excess fish food, they may begin to target weak fish and suck the slime coat off from them. The Plecos don’t want to kill the fish they are simply trying to get at the algae that has adhered to the slime coat itself. This is a bad situation and if you see it happening in your tank add some supplementary algae pellets at once.
Plecostomus will stake out a territorial spot in the tank and use it as its “home.” This home will be a place the fish feels safe and will spend most of the daylight hours there. If other fish try to take this area over the Pleco will reclaim it very aggressively. Plecos tend to like the undersides of rocks or the interiors of caves. If neither of these is available the Pleco will claim a corner of the tank as its own.
There are hundreds of breeds of Plecostomus with some of the fancier breeds having stripes (zebra Pleco) or exotic colored spots (gold nugget Pleco), some varieties even have a spiky growth over their nose (bristle nose Pleco). All of these breeds have heavy scales and armored heads that make them capable of living with aggressive fish including Cichlids. Because Plecos tend to grow to a large size and because they are aggressive to others of their own kind it is advised that no more than one be kept per 50 gallons.
Otocinclus catfish are far smaller than Plecostomus, ranging from 2 to 5 inches with most staying around the 3 inch mark, and are a social fish. Unlike most other freshwater aquarium catfish, Otos will get lonely if they are not kept in schools of at least three (preferably 6 or more).
There are two types of Oto, the Golden Oto which is predominantly gold with a large horizontal black stripe running from the tip of its nose to the base of its tail, the Zebra Oto is black with several vertical white bands encircling the body. Otos are voracious eaters and a team of three can keep a 29 gallon tank spotless; in fact, they may need additional algae wafers to supplement their diet after cleaning a dirty tank.
The Walking Catfish is the only known air-breathing freshwater aquarium catfish. It comes in both a standard black and albino variety. These catfish are extremely smart and will start to recognize and even come to their owners after a short while. They thrive in tanks that employ both water-based and land-based habitats. These fish will attain a length of almost a foot and are very aggressive (read “they will eat anything that they can get in their mouths”), so it is best that they are kept with only larger fish. They are also scaleless, covered in a mucus-like coating, so fine substrate is recommended.
Banjo catfish get their name directly from the shape of their bodies. They have flat heads and bodies that, from the top, form almost a circular shape that tapers back to a rigid tail—they look like guitars or banjos. They are multi-colored, often called cryptic color, ranging from brown to rust red in varying patterns. They also have a bumpy head. This combination of head and color makes them extremely hard to see in the riverbed. They are excellent at camouflaging themselves; in fact, you’ve probably missed more than a few in your shopping days. They are nocturnal and spend the day burrowed under the sandy bottom of the tank.
As far as size is concerned, the Banjo catfish can range from 2 inches all the way up to 2 feet. Most of the varieties available at local pet stores will top out around 6 inches but make sure you check with the staff to make sure.
Banjo cats are a schooling fish and do best in groups of up to five in a 55-gallon tank. They are not aggressive and will leave almost all fish (except fry) alone. They are omnivorous and enjoy a diet of flake food and brine shrimp or krill. They will not eat during the day so it is essential to feed the tank just before you turn off the lights for the night. They are an easy fish and can be quite interesting if you can figure out how to watch them (putting in red night lights sometimes helps as does using a bright white substrate).
Talking catfish are so named because when you take them out of the water they make a barking or grunting sound. There are two types, the striped Rafael and the spotted Rafael. Each of them can grow to a length of just about a foot, although when keep in smaller tanks (55 gallons or less) they tend to top out at the 5 to 6 inch range.
Rafaels are nocturnal and seldom move unless it is time for them to eat. They are not recommended for beginning fish keepers as they have a tendency to hide most of the time and don’t know when to stop eating so it is easy to over feed them. They are graceful swimmers when they do swim, gliding casually through the water like sharks. They are not picky eaters and will consume anything that fits in their mouth including very small fish like neons or fry. Other than eating smaller tank mates the Rafael is a great community fish. They have been known to devour whole tankfuls of snails in under a week.
The striped Rafael, in addition to its armor plating, has row upon row of herringbone-like spines along its body. If you were to try to pick one up by hand you’d probably get spiked. Catching them with a net is also not going to work as the spines tend to get hopelessly entangled in the mesh leading to a dangerous situation for the fish. The best way to catch one is in a plastic container. These freshwater aquarium catfish are among the most docile and unique in the entire hobby.
Upside Down Catfish
Upside down catfish are members of the Synodontis family of catfish. These freshwater aquarium catfish are mostly known for their habit of squeaking at each other as a form of communication. Most varieties are black with white or tan spots while there are some with the exact opposite colorings. Many of the Synodontis catfish come from the same lakes as African cichlids and are the preferred tank cleaners for these specialty tanks (Cuckoo and Even Spotted Squeakers to name two).
The most popular Synodontis is the Upside Down Catfish. This aquarium oddity is prized for its tendency to swim and feed in the inverted position. The small, 4 inch, size of the fish allows it to be kept in schools that only enhance their odd behavior. They eat flake food, pellet food, tubiflex worms and various plant matter. Being predominantly nocturnal, these fish will spend most of the daylight hours hiding in vegetation or caves. If there is sparse cover in the tank the upside down catfish will school together and find a vacant corner of the tank to claim as their own.
Sheatfish is the classification of what is commonly referred to as the Glass Catfish. Glass Cats, also known as Ghost Catfish, are a gorgeous and unique variety that has very little in common with most other catfish breeds. These catfish will not scour the bottom of your tank nor will they clean the algae from your tank walls or plants. These fish are an ultra passive schooling fish with a distinct look. They will not fight for food, in fact they will starve to death before competing with more aggressive community fish. Feed them flake foods and make sure to watch them so they do get enough to eat.
Glass Cats like a heavily planted tank where they have several places to hide and do quite well in a single species specimen tank. They will draw attention with their transparent bodies which allow viewing of the bone structure and internal organs. The Glass Catfish is an amazing fish but one that needs to be handled with care. It is not near as hardy as other catfish and will easily succumb to several common tank diseases including ich. Definitely not for the beginner, this catfish is best left to the experienced aquarist.
Long Whiskered Catfish
Even though there are several varieties of long whiskered catfish only one is really suitable for freshwater aquarium use, the Pictus Catfish. The Redtail and Tiger Shovelnose Catfish grow to sizes approaching 4 feet making them unsuitable for all but the largest aquariums and ponds and tank mates are hard to come by for these large aggressive fish.
The Pictus Catfish, on the other hand, only gets to be 11 to 12 inches long and will work in a 55 gallon home aquarium setup. This fish is still semi aggressive and will pick off smaller species like tetras and neons. They prefer to eat flake food or bloodworms and will graze on plants occasionally. The Pictus Cat is nocturnal but will swim around during the daytime and is comfortable as either a single fish or in a school.
The huge whiskers are the major attraction of this fish reaching all the way back to the caudal fin. The silver body is covered in medium sized black spots and their dorsal and pectoral fins have sharp barbs that make handling, and shipping in particular, quite a task. These spines are poisonous and do sting quite a bit if they catch in your skin.
With the almost unlimited choices in freshwater aquarium catfish, it is important to identify your needs prior to purchasing one. Just because it looks good in the display tank doesn’t mean it will look and perform well in your tank. Take care in your choices as each variety is compatible with vastly different ecosystems.
Anne on August 23, 2020:
Awesome! Through this article, we finally found out what kind of catfish we have—a walking catfish. Your description was completely accurate!
FBREDD on January 18, 2020:
very informative. Thank u
Genevive on March 04, 2018:
This is very informative if this what you want and most of them went well with my black diamond singray who came just as I was unboxing him!!!!
Banana man4365 on January 11, 2017:
I loved this article and all other ones
poetryman6969 on June 22, 2014:
love the colorful pictures!