Bristlenose pleco

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: may nibble soft.

Feeding

Mostly herbivorous and primarily nocturnal. Algae wafers, fresh or blanched vegetables (zucchini, cucumber, spinach, peeled peas) several times a week, and sinking pellets are all readily accepted. Despite the reputation, adults don't eat enough algae to keep themselves fed on a clean tank; a hungry bristlenose will start rasping plant leaves and damaging them. Driftwood is important for the species: Ancistrus graze biofilm and aufwuchs from wood surfaces and benefit from the cellulose, though they do not consume wood as heavily as Panaque species do. Repashy-type gel foods (Morning Wood, Soilent Green) work well as a staple because they stick to surfaces and don't foul water. Drop food after lights-out when the fish is naturally active and not in competition with daytime feeders. Use sinking food: swallowed air from floating food can cause bloating.

Nocturnal feeder; drop food after lights out.

Compatibility

• One of the most peaceful loricariids in the trade. Ignores other species almost completely and is safe with community fish, shrimp, and snails. Adult cherry shrimp are not eaten, though shrimplets are occasionally taken
• Two males in a small tank will compete for caves and fight. Either keep one male per cave's worth of territory, or use a longer tank with multiple caves spread out
• An underfed bristlenose has been reported attaching to flat-bodied tankmates (discus, angelfish) and rasping the slime coat. Keep well-fed to prevent this
• An effective biofilm and soft-algae grazer, but not a substitute for normal tank maintenance. Large algae problems are water-chemistry problems, not feeding problems

Origin and habitat

A small armoured catfish in the family Loricariidae, genus Ancistrus. The genus is the largest within the tribe Ancistrini, was erected by Kner in 1854, and contains species native to South America and Panama. The trade animal sold as 'common bristlenose' or 'bushynose' is best treated as Ancistrus cf. cirrhosus: most modern hobby fish are descended from A. cirrhosus stock (a species native to the Parana River drainage in Argentina and Uruguay, described by Valenciennes in 1836 as Hypostomus cirrhosus) but the trade form has been line-bred for so long, and possibly hybridised with other Ancistrus, that its precise identity can no longer be confirmed. Selectively bred lines in the trade include albino, long-finned ('butterfly' or 'veiltail'), piebald, xanthic, and super red forms. Imperial Tropicals confirms most hobby fish are line-bred from A. cirrhosus with possible hybridisation. The genus name derives from Ancient Greek agkistron 'fish-hook' or 'spindle hook' and refers to the curved cheek odontodes of mature males, not to the bushy facial tentacles as is often assumed; the German common name 'antennae catfish' is more literal about the tentacles. Males in particular grow elaborate fleshy tentacles on the head from sexual maturity onward; females may develop short bristles along the snout margin but not on the head, which is how the sexes are distinguished. Pectoral fin and opercular odontodes are also more developed in males. The body is covered in bony plates and the underside carries the suckermouth typical of the family, used both for clinging and for rasping food. Adults typically reach 10 to 13 cm in the trade form, with A. cirrhosus sensu stricto somewhat smaller (around 8.9 cm SL). The species is nocturnal or crepuscular; daytime activity in a community tank is more about food availability than natural rhythm. The synonym genera Pristiancistrus, Thysanocara, and Xenocara are now subsumed into Ancistrus.

Breeding

A cave spawner and one of the easiest plecos to produce at home. The male claims a cavity (coconut shell, PVC pipe, ceramic spawning tube, or a recess in driftwood) and cleans it carefully, then fans water out of the cave entrance to draw a receptive female inside. The female deposits an adhesive clutch of roughly 20 to 100 bright orange eggs on the ceiling or wall of the cave and then leaves; the male fertilises them and takes over all subsequent parental care. He guards the cave, fans the eggs continuously with his pectoral fins to keep oxygen flowing, and removes infertile or fungused eggs by mouth. The male rarely leaves the cave during the four to ten day incubation (faster at warmer temperatures, slower at lower ones) and does not feed during the period. Newly hatched fry stay in or near the cave for another two to five days while they absorb their large yolk sacs, and become free-swimming after that. First food is biofilm from surfaces in the tank, then crushed flake, mashed peas, or commercial fry food. Many keepers find fry appearing without any deliberate breeding setup, since a mature, planted tank with suitable caves and a sexed pair tends to produce broods on its own. Cooler water changes (a few degrees below normal) can trigger spawning, mimicking the rainy season. The sex ratio of fry has been reported as temperature sensitive.

Common problems

Starvation is the most common preventable problem: people buy the species as a 'cleanup crew' and never feed it, assuming algae will be enough. In a mature, moderately stocked tank a single fish may be sustained on biofilm and stray food, but most setups need supplemental algae wafers, blanched vegetables, and sinking pellets. The fish is also more dependent on driftwood than most aquarists expect; without it, digestion suffers slowly over time. Bloating from swallowed air is fairly common when only floating food is available, which is why sinking food is the rule. Bacterial infections around the facial tentacles of males can appear in poor water quality. The species is sensitive to aquarium salt (a common loricariid trait), so salt-based ich treatments should be avoided. The pectoral spines catch in fine-mesh nets and the odontodes can damage sponge filter media when the fish forces its way in; moving the fish in a rigid container rather than a net avoids both. Males are aggressive toward each other over breeding caves; two males in a tank under about 150 L will fight, and bristles sometimes tangle together in the process.

Bioload

Further reading

• Why your angelfish ate your neons
• How bioload actually works
• Stocking ideas by tank size