Oscar

Astronotus ocellatus

Animalia›Chordata›Actinopterygii›Cichlidae

📍 Amazon & Orinoco Basins, South America

Oscars are large, bold cichlids known for their personality and intelligence. They recognise their owners and can be hand-fed, but they are destructive tank inhabitants that will uproot plants and rearrange décor. They need very large tanks with robust filtration.

Size12"

Min Tank75g

aggressive

Zoneall

Care Guide

Diet

Oscars are carnivorous and require high-protein foods including quality cichlid pellets, earthworms, crickets, and frozen shrimp. Feed juveniles once daily and adults once daily, offering portions they can consume in 2-3 minutes. Supplement occasionally with live foods to encourage natural hunting behavior.

Behavior

Oscars are highly intelligent, bold cichlids that recognize their owners and can be hand-fed. They are aggressive and territorial, especially during breeding, and will uproot plants, rearrange décor, and chase smaller tank mates. They are active swimmers that patrol all tank zones and require substantial space to exhibit natural behaviors.

Breeding

Breeding Oscars in captivity is moderately difficult and requires pairs to be well-established in large tanks (100+ gallons). They are substrate spawners that lay eggs on flat surfaces and exhibit strong parental care, aggressively defending fry. Separate breeding pairs from other fish to prevent aggression and ensure fry survival.

Tank Mates

Severum

Similar size and temperament; both large South American cichlids that can coexist in spacious tanks with adequate territory

good

Jack Dempsey

Comparable aggression and size; requires 75+ gallon tank with plenty of space to minimize conflict

good

Firemouth Cichlid

Smaller than Oscar; may be bullied or eaten; only suitable in very large tanks with multiple hiding spots

caution

Bristlenose Pleco

Nocturnal bottom-dweller that avoids Oscar; helps control algae without competing for space

excellent

Silver Dollar

Schooling fish that may trigger Oscar predatory instinct; only viable in 100+ gallon tanks with fast-swimming space

caution

Common Diseases

Hole-in-the-Head (HITH)

Symptoms

Pits or holes developing on head and lateral line; loss of appetite; lethargy

Treatment

Improve water quality, perform frequent water changes, reduce stress, and consider activated carbon filtration; may require antiparasitic medication if severe

Ich (White Spot Disease)

Symptoms

White spots covering body and fins; excessive scratching against décor; rapid gill movement

Treatment

Gradually raise water temperature to 28-30°C, perform daily water changes, and treat with aquarium salt or ich medication; maintain excellent filtration

Fin Rot

Symptoms

Frayed or deteriorating fins; discoloration at fin edges; fin tissue loss

Treatment

Perform large water changes to improve water quality, remove any sharp décor, and treat with antibacterial medication if secondary infection occurs

Bloat (Dropsy)

Symptoms

Swollen abdomen; scales standing on end; lethargy; loss of appetite

Treatment

Improve water quality with frequent changes, feed high-quality foods, consider fasting for 1-2 days, and treat with antibiotics if bacterial infection is suspected