Oscar care guide
Oscar (Astronotus ocellatus) — minimum tank 400 L, temperature 22-28 °C, pH 6-8.
Compiled by Aquairi from published sources · Published · Updated
Overview
The Oscar (Astronotus ocellatus) is a large South American cichlid prized for its responsive, interactive behaviour and intelligence. It develops a powerful adult body with bold black, orange and red mottling; selectively bred Tiger, Red and Albino forms are widely traded.
Taxonomy
- Family: Cichlidae
- Genus: Astronotus
- Scientific name: Astronotus ocellatus
- Common synonyms: Tiger Oscar, Velvet Cichlid
Habitat
Native to the Amazon, Orinoco and Paraná-Paraguay river basins of Brazil, Peru, Colombia, Bolivia, Venezuela, French Guiana and Uruguay. The species inhabits slow, warm sections of large rivers and floodplain lakes, sheltering among submerged wood and overhanging vegetation.
Tank requirements
- Minimum tank volume: 400 L (105.7 US gal)
- Adult size: 25-35 cm
- Temperature: 22-28 °C (72-82 °F)
- pH: 6-8
- GH: 5-20 °dGH
- Water flow: moderate
- Lifespan: 10-15 years
Diet
A carnivore that takes small fishes, crustaceans and insects in the wild. In captivity it accepts high-quality cichlid pellets supplemented with frozen or thawed shrimp, mussel, earthworms and occasional gel foods; feeding live feeder fish is discouraged as it carries disease risk and offers poor nutrition.
Compatibility
Territorial and predatory; will eat any tank mate small enough to fit its mouth. Best kept singly or as an established bonded pair in a very large tank. Compatible only with large, robust cichlids of similar temperament such as Jack Dempsey, Firemouth and Silver Dollar, plus large Bristlenose or Common Pleco.
Breeding
A substrate spawner. A bonded pair excavates a flat rock or pit and lays several hundred eggs; both parents guard the clutch and fry, which become free-swimming after about a week. Sex is hard to determine outside spawning condition.
Conservation status
IUCN Red List: Least Concern. Wild populations are widespread and stable across the Amazon system and the species is also extensively captive-bred for the aquarium and food-fish trade.
Breeding Oscar
Overview
Oscar (Astronotus ocellatus) is a biparental substrate-spawning cichlid of intermediate breeding difficulty. It reaches sexual maturity around one year of age and continues to reproduce for 9-10 years. Given the large clutch size and adult size, breeding requires significant space.
Sexing
The species is widely regarded as sexually monomorphic and does not tend to show external sexual differences, making sexing difficult. Males may grow more quickly, and in some natural strains possess dark blotches at the base of the dorsal fin. The ovipositor becomes visible as an extension of the oviduct just before and during spawning.
Pair Formation
Because the sexes are hard to distinguish, the best way to obtain a pair is to start with a group of half a dozen or more youngsters that pair off naturally as they reach sexual maturity.
Breeding Setup
- A very large aquarium reflecting the fish's adult size
- Flat horizontal or vertical surfaces (such as flat rocks) as spawning sites
- Water within the species range of 22-28 °C and pH 6-8
- Robust filtration for the heavy waste load
Spawning Behavior & Trigger
Spawning may be related to the occurrence of rain. During courtship the pair selects and thoroughly cleans a generally flattened horizontal or vertical surface, then lays eggs on it. Smaller females lay around 300-500 eggs, while larger females can lay about 2,500-3,000 eggs. The eggs are white and opaque immediately after laying and typically change colour during the first 24 hours.
Egg & Fry Care
Oscars practise biparental brood care, with extended post-hatching parental care typical of cichlids. Once the fry are free-swimming they can safely be separated from the adults.
Common Challenges
Reliable sexing is the main obstacle, so pairs are best formed from a group. The very large clutch size means a breeder must plan for the resulting fry; sources caution against contributing to overpopulation of the species in the hobby.