Popular plecos

Plecos are loricariid catfishes — the suckermouth armoured catfishes of South and Central America — and the family is enormous. Only a fraction of it turns up in aquaria, and this guide gathers that fraction: the species an aquarist is actually likely to meet, from the unkillable bristlenose to the L-number plecos that change hands for serious money. What they share is the loricariid template: a flattened, armour-plated body, a ventral sucker mouth that lets them hold station on rock and wood in fast current, and largely nocturnal habits.

Diet sorts them more than looks do. Ancistrus and the otos are grazers that rasp algae and biofilm; the royal and clown plecos (Panaque, Panaqolus) are among the very few vertebrates that genuinely eat wood, and need driftwood in the tank as food, not just décor; the Hypancistrus L-plecos of the Rio Xingu and its neighbours are largely carnivorous despite their reputation as 'algae eaters.' Most want well-oxygenated water, clean substrate, and wood to graze and hide among — and several, the zebra pleco above all, come from rivers now altered by damming, which is part of why wild stock is scarce and tank-bred fish matter.

Each species below links to its full profile, distribution map and water tolerances; many carry an L-number badge where one has been assigned.