Bristlenose Catfish

Bristlenose Catfish are algae eating Catfish of the genus Ancistrus.   There are about 60 species in this genus and it is uncertain which species the common aquarium Bristlenose catfish comes from.   It may be Ancistrus cirrhosus but it is very likely to be a hybrid of two or more related species.

The Bristlenose Catfish species come from South America, mostly from the tropics although some species are found outside the actual tropics.


Males grow to about 15cm (6 inches) while females get to a little less than this at about 12 cm (5 inches).

Water Conditions

The Bristlenose Catfish is quite flexible in its water requirements.   It can live in water ranging from soft to hard, with a Gh range of from 2 to 20.   Acid, neutral or alkaline pH all seem OK, although I would not subject this fish to extremes.

Although this is a tropical fish, it is not very tolerant of high temperatures.   The generally recommended temperature range is from 23 to 27 degrees C (73 to 81 degrees F).   However, a prolonged temperature of 30 degrees C (86 degrees F) will cause these fish to die while they seem happy at well below the 23 degrees normally recommended minimum temperature.   I suggest a lower temperature than the upper part of the normally recommended range.

A water current from a power filter is a good idea.   Avoid excessive levels of ammonia, nitrites and nitrates.

Some aquarium safe wood is strongly recommended.The fish not only eat algae and other organisms growing on the surface of the wood, they also ingest a small amount of the substance of the wood, and this seems to be beneficial to them.

Sulphur drugs

There are reports that some common sulphur based drugs, including triple sulphur, are deadly to Bristlenose Catfish. I have never tested this, but I avoid using these medications in tanks with Bristlenoses.


The Bristlenose Catfish is an omnivore with a preference for vegetable matter.   They are specialised for eating algae, but this is not the only thing they eat.   This applies both in the wild and in an aquarium.   When there is a film of algae growing on a surface many other small organisms will live together with the algae.   The algae together with the associated organisms are referred to as aufwuchs.

In an aquarium, as well as the naturally growing algae, these fish will eat normal fish food, especially algae wafers.   Although they will eat high protein food like frozen bloodworms, this is not a good idea for a major part of their diet.   If they do not have enough fibre they can be in trouble quickly.

They also like vegetables like Zucchini, Cucumber and green Peas.   Usually Bristlenose Catfish do not eat aquarium plants, but will eat the algae and other things off the leaves.   I have heard of them eating plants, but this appears to be a response to a lack of other food.   I have never observed plant eating in this species myself.


The Bristlenose Catfish is a very peaceful fish except that the males are territorial.   Two males may fight, but I have never heard of a fatal encounter.

This fish can be kept with a very wide range of other fish.   They will not eat other fish, except baby fish that are not free swimming.   I have bred Bristlenose Catfish together with Guppies and have no trouble between the two species.   Even the newly born baby Guppies are not molested by the Bristlenose Catfish.

At the other extreme, Bristlenose Catfish can be kept with quite big and moderately aggressive fish without trouble.


The males get the bristles on the centre of their head while the females generally do not, although they may get a few on the front of the head, near their mouth.



Bristlenose Catfish breed in caves; the males will guard the eggs while they are hatching and the babies in the very early stages after hatching.

The male won't always like the cave made for him by the aquarist and will often modify it or build his own cave by removing the gravel from under a rock or a piece of driftwood.

One male can breed with several females, and sometimes may have more than one batch of eggs and babies in different stages of development.   One large female can produce up to 200 eggs at one spawning.

The exact temperature does not seem to be critical for breeding.   In the breeding tank in our shop I have set the thermostat at 20 degrees C (68 degrees F).   They are breeding well.   Because of our climate and the conditions in the shop that the temperature will average well above the thermostat setting.

Raising the Fry

The male guards the eggs and the babies, until they are free swimming.   Even after the fry are free swimming, the males, and possibly the females, will sometimes chase other fish away from the babies. Partly because of this guarding behaviour, they will sometimes breed successfully in community aquariums.

The babies are quite large for aquarium fish fry.   As soon as they are free swimming they will eat the same food as the parents.

Other Common Names

The “Bristlenose Catfish” is also called the “Bushynose Catfish”, the “Bristlenose Pleco” and the “Bushynose Pleco.   The Pleco part of the name is because of their relationship to the Pleco, or Plecostomus fish.


As mentioned earlier, the Bristlenose Catfish commonly kept in aquariums are certainly of the genus Ancistrus, but the actual species is uncertain.   They may be Ancistrus cirrhosus, but the various species of the Ancistrus genus readily hybridise, usually producing fertile young.   It is very likely that there have been other species crossed into the aquarium Bristlenose Catfish; perhaps including Ancistrus pirareta from Paraguay, Ancistrus multispinis from Brazil or Ancistrus irradiates from Columbia.

There is also no reason to assume that all the Bristlenose Catfish around in aquariums and shops are of the same species or mixture and we cannot even assume that all are inter fertile.


Pest Fish

Do not allow any fish or other pet to escape into the wild.   Even an apparently harmless creature can severely disrupt ecosystems.

Sources and Credits

The identity of aquarium Bristlenose Catfish:

Aquarium Industries Care Sheet.