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Fish Freshwater Care: medium Semi-aggressive

Bigeye Cichlid

Acaronia nassa
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Other names: Acaronia, Nassa, Acara nassa
Group: American cichlids · Family: Cichlidae · Origin: South America — Amazon basin and the Guianas

An 18 cm Amazon cichlid that lies in ambush for small fish with its large eyes and huge protrusible mouth. It looks calm but eats any fish that fits in its mouth.

Will it suit my tank?

Last updated October 16, 2026

Temperature
25–30°C
pH
5.5–7
Hardness
2–10 dGH
Adult size
18 cm
Minimum tank size
250 liters
Social structure
Pair
Male–female ratio
Tek ya da kendiliğinden eşleşmiş çift
Swimming zone
Middle
Diet
Carnivore
Breeding
Substrate spawner

Water parameters

Temperature25–30°C
pH5.5–7
General hardness (GH)2–10 dGH
Recommended range
Eats small fish Eats shrimp Suitable for planted tanks

Overview

October 16, 2026 · Suggest an edit

The bigeye cichlid takes its name from its large eyes, which cover much of its head. With a dark band running through the eye, a dark blotch in the middle of the body and an olive–brown body, it hides easily among plants and roots. With its huge mouth that can extend forward, it is a typical ambush predator: it waits motionless and swallows an approaching small fish in a single lunge. It is rare in the trade and is mostly kept by enthusiasts.

Tank Setup

October 16, 2026 · Suggest an edit
  • At least 250 liters and 120 cm of length for a single fish or a pair.
  • Dense plants, roots and leaf litter; dim light.
  • Soft, slightly acidic, clean water; change 30% weekly.
  • Gentle current; avoid crowded, noisy setups.

Diet

October 16, 2026 · Suggest an edit

Carnivorous. Offer frozen mysis, shrimp, bloodworms and fish fillet; some individuals accept carnivore granules over time. Live feeder fish carry a risk of disease.

Behavior and Compatibility

October 16, 2026 · Suggest an edit

It stays calm and motionless all day; it usually does not clash with fish of its own size. It sees any fish that could fit in its mouth as prey.

Good companions: calm fish of its own size: severum, festivum, Geophagus species, large plecos, silver dollars.

Avoid: tetras and other small fish, shrimp, large aggressive cichlids.

A short profile for this species

The Bigeye Cichlid 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