Species profile

Javanese Ricefish

Oryzias javanicus

Common names: Javanese Ricefish, Java Medaka, Javanese Medaka

Recognized speciesRicefish

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Adult size

Up to 3.5 cm

Countries of origin

Good fit for your tank?

Good fit for

A peaceful community tank with similar-sized fish
A small, well-kept nano tank
A keeper with room for a proper group of 10 or more

Think carefully if

You only want to keep one or two, because this fish needs a group of 6 or more

A small, peaceful fish from coastal Southeast Asia, usually from brackish water, and it does well in hard water with a little salt. Keep a group of at least 6 in 40 litres or more.

Appearance and Identification

A small, peaceful fish from coastal Southeast Asia, usually from brackish water, and it does well in hard water with a little salt. It is fairly easy to breed.

Check the scientific name when buying, as common names vary between sellers and countries.

Mature females are usually rounder in the belly, and males are usually slimmer and often brighter.

Tank Requirements

Suggested filter: About 160–200 litres an hour
Suggested heater: About 50–75 W for this tank
Minimum tank volume: 40 litres
Minimum tank length: 45 cm
Minimum group size: 6
Recommended group size: 10
Activity level: Active
Flow preference: Low to moderate
Planting preference: Moderately planted
Lid recommended: Yes
Jumping risk: Moderate

A long tank with open swimming water, plants around the edges and steady filtration suits this fish. A darker substrate and some floating plants usually bring out its colour.

Behaviour and Tankmates

Active and social, and most settled when kept with its own kind.

Keep a group of at least 6, and more if you can. Larger groups are calmer and show better colour and behaviour.

Not territorial, although males may spar and display.

Suits a community of similar-sized, peaceful fish that like the same water. Avoid large predators, which will treat it as food. It may eat baby shrimp.

Check tankmates for this species

Water Parameters

Temperature: 24–29 °C
pH: 7–9
GH: 5–25
Stability importance: Important

Fairly tolerant of different water, if it is clean and stable.

Parameter caveat

Keep up regular water changes, and acclimatise new fish slowly.

Feeding

Diet types: Omnivore
Feeding frequency: Daily
Preferred foods: Small flake or micro pelletsA good staple. Feed small amounts that are eaten within a couple of minutes.
Frozen or live daphnia and brine shrimpOffer a few times a week for colour and condition.
Small bloodwormA rich treat rather than a daily food.

A small surface-feeding omnivore. Feed fine flake and small frozen foods.

Feed small amounts, and remove anything left after a few minutes.

Breeding

Breeding type: Egg Layer
Breeding difficulty: Easy
Parental care: None
Baby foods: InfusoriaNeeded for the first days, because most fry are very small.
Newly hatched brine shrimpIntroduce as soon as the fry can take it.

Lays eggs on plants or in the substrate, depending on the species, and many keepers collect the eggs to raise separately. Some species have eggs that survive long dry periods.

Habitat and Origin

Geographic origin: Indonesia, Malaysia, Singapore, Southeast Asia, Thailand
Natural habitat: Brackish Water, Freshwater Stream, Swamp
Aquarium contexts: Nano Aquarium, Planted Aquarium
Audience level: Beginner

Classification

Profile type: Recognized species
Genus: Oryzias
Family: Adrianichthyidae
Species group: Fish, Ricefish

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Good fit for your tank?

Good fit for

Think carefully if

Appearance and Identification

Tank Requirements

Behaviour and Tankmates

Water Parameters

Feeding

Breeding

Habitat and Origin

Classification

Have you kept this species?

Other Ricefish

Medaka (Japanese Ricefish)

Platinum Medaka

Celebes Ricefish

Daisys Blue Ricefish

Guides for keeping this fish

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