Monoculus peacock bass

Cichla monoculus

Also known as Popoca peacock bass, Mono peacock bass

FreshwaterFish

Care at a glance

Temperature: 77–86°F (25–30°C)
pH: 6.0–7.5
Adult size: 27.6 in (70 cm)
Minimum tank: 528 gal (2,000 L)
Temperament: Aggressive
Social behavior: Solitary
Tankmates: Tankmates with caution
Swim level: Middle
Difficulty: Difficult
Breeding: Hard
Rarity: Rare
Origin: Amazon lowlands
Family: Cichlidae

Overview

The monoculus peacock bass is a pond-scale predator, so take the specs seriously: a single fish needs a tank of at least 2000 liters, really an indoor pond, and it is best kept alone. It is a strong, active swimmer that patrols the middle water and will eat any tankmate it can fit in its mouth, so companions have to be large, fast and chosen with great care, if you keep any at all. Feed meaty foods such as whole fish, prawn and large sinking pellets, and back it with heavy filtration and current. This is a decades-long commitment to a fish that outgrows almost every home aquarium.

In the wild

Cichla monoculus ranges through the warm lowland Amazon, hunting in lakes, lagoons and slow channels. Give it warm, soft to neutral water: a temperature range of 25–30 C and a pH of 6.0–7.5. Its natural water is often quite acidic, so it takes lower pH well. Provide a large open swimming area over sand, with big pieces of wood for structure and strong mechanical and biological filtration, since a fish this size produces a heavy load of waste.

Good to know

Cichla monoculus belongs to the cichlid family and is a giant among aquarium fish, reaching about 70 centimeters. It was described by Agassiz in 1831, and its name means one-eyed, for the single large eyespot at the base of the tail. Like other peacock bass it is a biparental substrate spawner that cleans a site, lays a large clutch and guards the fry fiercely, but it is a hard fish to breed indoors simply because of the space a pair demands.

Did you know

The dark eyespot at the base of the tail, which gives the fish its name, is thought to work as a decoy: it mimics the real eye and may draw fin-nipping attackers toward the tail end instead of the head.