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Fish Freshwater Care: hard Semi-aggressive

Scarlet Pleco (L025)

Pseudacanthicus pirarara
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Other names: L025, Scarlet cactus pleco, Pseudacanthicus pirarara
Group: Plecos and suckermouth catfish · Family: Loricariidae · Origin: South America — Rio Xingu and Rio Iriri (Pará, Brazil)

One of the most spectacular giant plecos, with a spiny dark body and red-orange fin edges. It reaches 45–50 cm, is territorial and carnivorous, and needs a very large aquarium.

Will it suit my tank?

Last updated October 16, 2026

Temperature
26–30°C
pH
6–7.5
Hardness
2–10 dGH
Adult size
50 cm
Minimum tank size
1000 liters
Social structure
Solitary
Swimming zone
Bottom
Diet
Carnivore
Breeding
Substrate spawner

Water parameters

Temperature26–30°C
pH6–7.5
General hardness (GH)2–10 dGH
Recommended range
Eats shrimp Eats snails Suitable for planted tanks

Overview

October 16, 2026 · Suggest an edit

The scarlet pleco was known for years by the number L025 and was described in 2014 as Pseudacanthicus pirarara. Its body is covered with hard, spiny plates (the name "cactus pleco" comes from this); the red-orange colors on its fins make it a much sought-after species.

Juveniles are expensive and sold small, but adults are large, powerful fish reaching 45 cm standard length. Because of its territorial nature and size, it is only for experienced keepers and very large aquariums.

Tank Setup

October 16, 2026 · Suggest an edit
  • At least 1000 liters and 200 cm length for one adult.
  • Very powerful filtration, flow and aeration.
  • Large caves and sturdy rock piles; 27–29°C.

Diet

October 16, 2026 · Suggest an edit

An omnivore leaning toward a carnivorous diet. Make pieces of mussel, shrimp and fish, krill, bloodworms and protein-rich tablets the staple; a small amount of vegetables can also be given.

Behavior and Compatibility

October 16, 2026 · Suggest an edit

Powerful and territorial. It can show serious aggression toward its own kind and other plecos; with its spiny body it can injure other bottom dwellers.

Good companions: Large, fast, robust fish: large Central and South American cichlids, large characins (in a very large aquarium).

Avoid: Other plecos, small and slow bottom dwellers, shrimp, snails.

A short profile for this species

The Scarlet Pleco (L025) page has the basics, but the sections below have not been written yet. If you keep this species, write a section from your own experience; it will be published under your name after editor approval.

Tank mates

This list is calculated automatically from the species profile and grows as new species are added to the catalog. Try it in the planner for a definite answer.

Usually compatible

Should not be kept together

Hobbyist notes

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Change history and contributors
  1. Page created · October 16, 2026