Common pleco

Quick facts

Adult size

50 cm

Lifespan

can live up to 20 years

Tank zone

bottom

Temperament

peaceful

Difficulty

intermediate

Water parameters

Temperature

22–30°C

pH

6.5 to 8.0

Hardness

4 to 25 dGH

Tank requirements

Minimum volume

450 L

Minimum length

180 cm

Flow

moderate

Lighting

any

Substrate

any

Driftwood

preferred

Hiding spots

needed

Feeding

Diet: omnivore, feeds primarily at the bottom.

Algae wafers, sinking pellets, blanched vegetables (zucchini, cucumber, spinach). Algae eating decreases significantly with age; adults are mostly omnivorous scavengers.

Vegetable matter required (algae wafers, blanched zucchini, spinach).

Nocturnal feeder; drop food after lights out so it can eat without competition.

Compatibility

• The most-mis-sold fish in the freshwater hobby. Sold at 5 cm to people with 75 L tanks; reaches 40–60 cm and needs 450 L+
• Algae-eating reputation is overstated; useful as juveniles, mostly stops as adults
• Will rasp the slime coat of slow flat-bodied fish (discus, angelfish, sleeping cichlids) at night, causing wounds and stress
• Heavy waste producer; a single adult overwhelms filtration sized for a typical community tank
• Bristlenose pleco (Ancistrus) is a 12 cm alternative that stays small, eats algae as an adult, and fits in standard tanks. Recommend that instead in nearly all cases

Habitat

Native to tropical South America, found across the Amazon, Orinoco, and other major river systems. The species sold as "common pleco" in stores is usually Hypostomus plecostomus or Pterygoplichthys pardalis (the latter is more common but both are sold under the same name). Established invasive populations exist in Florida, Texas, Hawaii, Australia, and many tropical Asian countries. One of the most problematic aquarium-trade invasive species globally.

Breeding

Not bred in home aquariums. Commercial breeding occurs in outdoor ponds in Florida and Southeast Asia. Wild common plecos spawn in deep burrows along riverbanks during the rainy season. The adult size (40–50 cm) and space requirements make home breeding impractical. If a common pleco outgrows your tank, do not release it; they're an invasive species in many warm-water regions worldwide.

Common problems

The number one issue is adult size. Stores sell them at 5–8 cm as "algae eaters" without mentioning they grow to 40–50 cm and live 15-20 years. A 200 L tank that seemed fine for a juvenile is hopelessly undersized for an adult common pleco. They also stop eating algae as they grow and become primarily scavengers. The second issue is aggression: adult common plecos become territorial and can injure tankmates with their armored body and powerful tail.

Bioload

Bioload coefficient: 8.0 (very large messy fish; produces enormous quantities of waste, comparable to a large adult goldfish).

Bioload coefficients are calibrated against the neon tetra as the anchor (1.0). See the methodology page for the formula and how each value was derived.

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size