Plecos and suckermouth catfish

Plecos range from two-inch otocinclus to common plecos that outgrow most tanks, so adult size is the first thing to check. Many graze algae but still need wood and sinking food of their own. Profiles list adult size, tank size and diet for each species.

Tank size: 11–264 gal; 11 gal (40 L) to 264 gal (1,000 L); half the list needs 42 gal (160 L) or more
Temperature: 77–84°F; 25–29°C, most of the list
pH: 6.0–7.4; Most of the list
Difficulty: 6 easy; 102 medium · 18 difficult
Temperament: 98 peaceful; 23 mostly peaceful · 5 aggressive

126 species and 4 varieties

How big do plecos get

Anywhere from 2 inches to nearly 3 feet, which is why adult size is the first line on every profile here. The otocinclus and the dwarf spiny pleco stay around 2 inches (5 cm). The bristlenose pleco, the one most people should buy, stops near 5 inches (12.5 cm). The common pleco sold as an algae eater for a 20 gallon reaches 16 inches (40 cm) and lists 85 gallons (320 liters); the sailfin and leopard sailfin plecos reach 18 to 19 inches (45 to 48 cm) and the royal pleco 17 inches (43 cm) on 100 to 125 gallons (380 to 473 liters). The adonis pleco reaches 35 inches (90 cm) and lists 264 gallons (1000 liters). Shops sell all of these at 2 to 3 inches, so the name on the tag is the only warning you get.

Plecos for a community tank

The small plecos are some of the best community fish there are. The bristlenose pleco grazes algae, stays around 5 inches (12.5 cm) and is happy from 20 gallons (75 liters) with a piece of driftwood to rasp. The clown pleco stays at 3.5 inches (9 cm) in the same tank, eats wood more than algae, and is one of the few in the list marked easy. The whiptail catfish is a 4 inch (11 cm) twig of a fish for a calm 20 gallon. The bloodred tiger pleco stays at 3 inches (8 cm) and wants a bit more room at 40 gallons (160 liters). Otocinclus are the small algae eaters for a planted tank, in a group of six, but only once the tank is mature enough to grow the film they live on.

L-numbers

Many plecos are sold by an L-number rather than a name: L204, L264, L034. The numbers were assigned by the German magazine DATZ to plecos that arrived in the trade before science had described them, and the trade kept using them even after the species got names. Where the shops still lead with the number the catalog keeps it in the name, so you can search for the number on the tag. The flash pleco L204 stays at 5 inches (13 cm) and wants 40 gallons (150 liters); the medusa pleco L034 reaches 6 inches (15 cm) on the same footprint; the candy striped pleco L015 is a 5 inch (12 cm) fish for 30 gallons (115 liters); the sultan pleco L264 reaches 9 inches (22 cm), lists 65 gallons (250 liters) and is marked difficult.

Not every pleco eats algae

The bristlenose, the otocinclus and the clown pleco graze, and even they need feeding. Most of the fancy plecos do not eat algae at all. The zebra pleco and its Hypancistrus relatives are meat eaters that want frozen and sinking protein foods; the gold nugget pleco is marked difficult largely because it starves quietly in tanks where everyone assumes it is grazing. The royal pleco and the clown pleco are wood eaters and must have driftwood in the tank, not as decoration but as food. Feed every pleco after the lights go down, when the mid-water fish are not competing: wafers, vegetables such as zucchini and cucumber, and frozen foods for the carnivores.

Warm, clean, moving water

Most plecos come from Amazon and Orinoco tributaries and list 77–84°F (25–29°C) and neutral to slightly acid water. Many of the small fancy species, the zebra pleco among them, come from the Rio Xingu and want the warm end of that range plus strong flow and high oxygen; a still, cool tank is a slow death for them. Give every pleco a cave of its own. Males hold caves and defend them, and two of the same species in a small tank will fight over the best one. The otocinclus are the exception and go in groups.

By the numbers

Smallest

Largest

Easiest to keep

Most peaceful

Fits a 20 gallon tank

Fits a 30 gallon tank

FAQ

Common questions

How big do plecos get?

From 2 inches (5 cm) for otocinclus and the dwarf spiny pleco to 16 to 19 inches (40 to 48 cm) for the common, sailfin and royal plecos. The adonis pleco reaches 35 inches (90 cm). The bristlenose stays near 5 inches (12.5 cm), which is why it is the usual recommendation.

Do plecos eat algae?

Some do: bristlenose, otocinclus and clown plecos graze. None of them can live on algae alone, and the zebra, gold nugget and most other fancy plecos are meat eaters. Feed wafers, vegetables and frozen food after dark.

What size tank does a bristlenose pleco need?

20 gallons (75 liters) with a piece of driftwood. It reaches about 5 inches (12.5 cm).

What size tank does a common pleco need?

85 gallons (320 liters). It reaches 16 inches (40 cm) and produces a great deal of waste.

Do plecos need driftwood?

The wood eaters (royal and clown plecos) must have it. Bristlenose and many others rasp it for fibre and do better with it. The meat-eating Hypancistrus do not need wood but want caves.

Can you keep two plecos together?

Most are territorial toward their own species and toward similar plecos, especially over caves. One per tank unless the tank is large and every fish has a cave. Otocinclus are the exception and go in groups of six.

What do the L-numbers mean?

Catalogue numbers given to plecos by the German magazine DATZ before the species were formally described. The trade still uses them, so the catalog keeps the number in the name where the shops do.

Index