Scientific Name: Ancistrus spp.

Breeding Strategy: Cave spawner.

Ease of Breeding: Easy.

 Introduction: These catfish are perennially popu­lar, not just for their novel looks but for their industriousness: Within days of adding a bristlenose to a tank, every trace of algae will be gone. These catfish breed fairly easily in community or species tanks.

 Sex Differences: Mature males have much longer "bristles" than females, and tend to be larger.

 Water Conditions: Although not critical, bristlenose seem to prefer water that is on the acidic side; aim for a pH of between 6.5 and 7.0, and hardness of no more than 10 dH. Temperature should be between 75° and 80°F.

 Equipment: A single pair can be bred in a 15-gal-lon tank, but will also breed in a community tank, with size depending on the needs of the other occupants. Make sure there are plenty of hiding places, such as PVC pipe, flowerpots tipped on their sides, and bogwood, which bristlenose will both eat and hide under. They also appreciate a dense fringe of plants around the perimeter of the tank. Add a filter (either sponge or power), an air-stone, and a pump, since bristlenose like well-oxygenated water.

 Conditioning and Triggers: Condition on shrimp pellets, and vegetable matter such as parboiled zucchini or cucumber. A large water change sometimes seems to trigger spawning, as does a slight increase in temperature. Some breeders also report these fish spawn more readily in the late autumn.

 Spawning: Some bristlenose catfish spend days courting; others get right down to business. The male stakes out a nest site in a flowerpot, coconut cave, or piece of PVC pipe, and the female joins him, laying a clutch of semi-adhesive, amber-colored eggs. After the male fertilizes them, the female departs and the male remains, fanning the eggs with his fins to aerate them.

 Brood Size: Fifty or more.

Fry Care: The male guards the nest until the eggs hatch, usually in three to five days. The fry become free swimming within a week after that. Feed crushed vegetables such as blanched lettuce, peas, and zucchini, as well as baby brine shrimp and minced bloodworms. Keep in mind that bristlenose are bottom feeders, so if they spawn in a community tank, it's important to make sure some of the baby brine shrimp make it all the way to the bottom without being snatched up by other fish. You can also put rocks in jars of tank water on a sunny windowsill until they develop a good coating of algae, then put them in the tank for the fry to feed on. Change 10 percent of water daily.

 Special Note: Some female Ancistrus have been observed laying eggs in the nests of males already guarding fry—possibly because those males have proven their parenting skills. Some scientists theorize that the bristles on the male's nose, which somewhat resemble larval fry, may trick a female into thinking a male is a good parent and mating with him.