There are many different species within the genus Ancistrus, and it is often difficult to tell the species apart. I personally breed a species which might be Ancistrus temmincki, but I'm not sure. Bristlenose Catfishes are also called Bristlenose Plecos or "ordinary" Ancistrus. They are especially appreciated because they like to eat algae in the aquarium.

For Bristlenose Catfishes to feel really good they should be provided with a piece of driftwood, for example a mangrove root, that they can gnaw at, because their digestion benefits from the cellulose in the wood. Bristlenose Catfishes always try to stay close to the substrate or other objects. They can attach themselves by sucking with their mouths and scrape algae with their specially adapted teeth. The males can grow to about fifteen cm (about six inches) and the females can grow to about twelve cm (about five inches). The males get big, soft outgrowths on their heads that look like deer antlers. These outgrowths are missing or occur very sparsely among the females. Their natural habitat is the Amazon in South America.

The male chooses a cave in the aquarium, for example under a root, in a plastic tube, in a bamboo tube or a coconut shell. He usually stays there most of the day except at feeding time. If a female in the aquarium is ready to spawn the male will entice the female into the cave. This usually takes place in the evening after the lights are out. (The first time I observed the actual spawning, was when I happened to look into the aquarium one hour after the timer had shut off the light.) The male waves his caudal fin and the female swims into the cave. This is repeated until the female has laid all her yellow eggs, about fifty to one hundred, but sometimes more or less depending mainly on the size and condition of the female. The eggs swell to a diameter of about three to four millimetres (about 0.10 to 0.15 inches). The eggs resemble mustard seed. A period of several weeks follows, after the spawning is finished, when the male guards the eggs and the fry. During this period the male eats almost nothing so it is important that he is in good condition in advance.

The fry leave the cave after they have consumed their yolk sacs. This is usually about two weeks after hatching. If the aquarium is filled with yummy algae the fry will have plenty of food, otherwise you have to supply food for the fry in other ways. Very young fry do not understand enough about the situation to come out at feeding time, like the older fry do. You may have to catch the fry and put them in a "fry cage" or a nursery aquarium by themselves if they have problems surviving. If you use half of a coconut shell as a cave, then it is easy to just shake the fry out just before they are ready to leave the cave on their own. (It is a lot more difficult to catch the fry once they have already left the cave.) It is a good idea to protect the fry this way if you have other fishes in the aquarium that want to eat the tiny fry, or if the filter intake is not protected so the fry risk getting sucked into the filter. In a fry cage or a grow out aquarium it is easy to feed the fry. The fry can be housed in the fry cage or nursery aquarium for about a month before you put them in a larger aquarium. I have raised lots of fry this way.