Oscar

Overview

Oscar (Astronotus ocellatus) is a freshwater aquarium fish for aquariums where the layout leaves enough swimming room and the water stays stable.

Use these values as planning checks, then make sure the aquarium still has room for behavior, group needs, and calm community fish.

Care requirements

With a Intermediate – Advanced care level, Oscar is best for aquarists who can keep water quality steady and plan compatibility before adding the fish.

Plan the aquarium around the group, not just one individual.

With a lifespan of up to 20 years, this is a fish to plan for long term rather than an impulse addition.

Aquarium size and space needs

An aquarium of 900 L or larger can be a reasonable starting point, but it should not be read as permission to overstock.

At up to 45 cm, Oscar stays small, but a group still needs room to move, feed, and avoid constant competition.

A group of 5 or more should have enough room for movement and feeding.

Water parameters

The temperature range for this fish is 22 to 25 °C, which fits many tropical freshwater aquariums. Choose other fish with overlapping temperature needs.

The pH range for this fish is 6 to 8. That points to a broad freshwater range, but stability is more important than sudden corrections.

The GH range for this fish is 5 to 20 dGH. That gives some flexibility, but sudden changes are usually more stressful than a stable value that is slightly imperfect.

Temperament and compatibility

Oscar needs more careful companion choice because the temperament data suggests space, boundaries, or similar-sized fish may matter.

If kept in a group of 5 or more, the aquarium should have enough swimming room for the group rather than being planned around a single fish.

Swimming zone and behavior

Because this species is best planned as a group of 5 or more, plan the aquarium around the group rather than a single fish.

Feeding

As an omnivore, Oscar should receive a varied diet rather than one repeated food type.

Before adding this fish

Use this checklist before treating the profile as a match for an existing aquarium.

• Plan for an aquarium of 900 L or larger.
• Make sure the aquarium has enough open swimming room for the group.
• Choose other fish with overlapping temperature needs.
• Keep pH stable within the listed range instead of making sudden corrections.
• Choose other fish carefully around this temperament.
• Plan for a group of 5 or more.
• Offer a varied diet that matches this species.