Fish
Oscar
Astronotus ocellatus
Origin: Amazon and Orinoco basins: Peru, Colombia, Brazil, Bolivia
Also known as: Tiger Oscar, Velvet Cichlid, Astronotus ocellatus
Fact sheet
- Size
- 35 cm
- Lifespan
- 15 years
- Minimum tank size
- 400 L
- Temperature
- 23–28 °C
- pH
- 6–8
- Hardness GH
- 5–20 °dH
- Temperament
- Aggressive
- Social behavior
- In pairs
- Swimming zone
- Bottom, Middle
- Diet
- Carnivore
- Jumps out
- No
- Eats plants
- No
Varieties
Overview
The Oscar (Astronotus ocellatus) is one of the most iconic large cichlids in the aquarium hobby, first described by Agassiz in 1831. Native to slow rivers, flooded forests, and still waters of the Amazon/Orinoco basins with warm, soft, slightly acidic water. Renowned for its intelligence — Oscars recognize their owners and can learn to take food from the hand. Introduced as invasive in Florida, Australia, and parts of Asia.
Appearance
Wild fish reach 35–45 cm and 1.5 kg; aquarium specimens typically 25–30 cm. Body deep, robust, with large upturned mouth. Wild type: dark olive-green with irregular orange spots; characteristic eye-spot (ocellus) at the caudal peduncle.
Care
Minimum 450–600 L for a pair. Temperature 23–28°C, pH 6.5–7.5. Powerful filtration essential — heavy bioload. Coarse substrate or bare bottom; they rearrange and destroy delicate décor.
Feeding
Predominantly carnivore: large sinking cichlid pellets, frozen/live worms, prawns, fish. Avoid feeder fish due to disease risk.
Compatibility
Aggressive toward smaller fish — will eat anything that fits in the mouth. Best with species of similar size: large South American cichlids, large plecostomus.
Breeding
Substrate spawner. Pair cleans large flat surface; female lays 300–1000 eggs. Both parents guard intensely, transferring larvae to pits. Fry free-swimming at 5–7 days.
Fun facts
Oscars can recognize individual owners and exhibit conditioned responses, earning the nickname 'river dog.' Lifespan up to 15 years. IUCN: Least Concern.