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Mikolji's oscar

Astronotus mikoljii

Also known as Astronotus mikolji, Orinoco oscar

FreshwaterFish

Mikolji's oscar (Astronotus mikoljii)

Care at a glance

Temperature
77–86°F
25–30°C
pH
5.5–7.2
Adult size
11.4 in
29 cm
Minimum tank
132 gal
500 L
Temperament
Aggressive
Social behavior
Solitary
Tankmates
With caution
Swim level
Middle
Diet
Carnivore
Difficulty
Difficult
Breeding
Substrate spawner · Hard
Rarity
Rare
Family
Cichlidae
Origin
Orinoco basin and Gulf of Paria drainages

Overview

Mikolji's oscar is a large, aggressive predator for a very big tank. It is a fish for experienced keepers and a long-term commitment.

Did you know

The team that described Mikolji's oscar in 2022 was led by the Venezuelan ichthyologist Oscar Lasso-Alcala. The naming was billed, only half in jest, as an Oscar describing an oscar.

Caring for the Mikolji's oscar

Keep Mikolji's oscar on its own or as a single proven pair, rather than in a group. It needs a tank of at least 132 gal (500 L), with open swimming space over a sand floor. Add some large water-worn wood or rock for cover, and use robust or artificial plants. A fish this size eats soft plants and redecorates to taste.

Keep the water warm and soft to neutral, at 77 to 86°F (25 to 30°C) and a pH of 5.5 to 7.2. Expect a lot of waste, so run strong filtration and keep up with water changes.

Feed meaty foods such as prawn, mussel and earthworms, along with quality pellets. It cruises the middle of the tank and will eat any tank mate small enough to swallow. Choose companions with real care, since only big, robust fish stand a chance, and many keepers simply keep it alone.

Like other oscars, it is a biparental substrate spawner. It is rated a hard breeder in aquaria, because it needs size, a settled pair and clean water to spawn.

Good to know

Astronotus mikoljii belongs to the cichlid family and was named for Ivan Mikolji, the Venezuelan explorer, artist and underwater photographer. It is the Orinoco's own oscar, long confused with the widespread Amazonian Astronotus ocellatus.

In the wild

Astronotus mikoljii comes from the Orinoco basin and the Gulf of Paria drainages of Venezuela and Colombia. It lives in warm lagoons and slow river channels.

Common questions

What size tank does a Mikolji's oscar need?

A Mikolji's oscar needs at least 132 gal (500 L). It spends most of its time in the middle.

What temperature and pH does a Mikolji's oscar need?

A Mikolji's oscar is comfortable at 77–86°F (25–30°C) with a pH of 5.5–7.2.

What does a Mikolji's oscar eat?

A Mikolji's oscar is a predator that eats meaty foods such as prawn, mussel and earthworms. Give it quality pellets as well.

How big does a Mikolji's oscar get?

An adult Mikolji's oscar reaches about 11.4 in (29 cm).

How does a Mikolji's oscar breed?

Mikolji's oscars are biparental substrate spawners, like other oscars. Breeding them in aquaria is hard, since they need size, a settled pair and clean water to spawn.

Related species