Moroko (Gnathopogon caerulescens)

Family: Cyprinidae

Moroko — a Cyprinidae from Japan, mostly peaceful; some species nip fins. Reaches 5–8 cm; shoaling; keep in groups of 6 or more. 10–24 °C.

Care parameters

Water temperature: 10–24 °C
pH: 6.5–7.5
GH hardness: 5–15 dGH
Adult length: 5–8 cm
Minimum tank: 60 L
Water layer: Middle of the water column
Difficulty: Moderate
Temperament: Mostly peaceful; some species nip fins
Origin: Japan

Species overview

A Cyprinidae species native to Japan: Gnathopogon caerulescens lives middle of the water column over gravel. Mostly peaceful; some species nip fins. Adults reach 5–8 cm. It is one of the aquarium-kept Gnathopogon species we profile, alongside Gnathopogon herzensteini, Gnathopogon imberbis, Gnathopogon polytaenia.

Native biotope

Habitat: Clear streams and rivers over gravel
Flow: Moderate, well-oxygenated current
Dissolved O₂: Appreciates well-oxygenated water

Aquascape & hardware

Substrate: Fine gravel and sand
Hardscape: Water-worn stones and driftwood
Plants: Hardy rooted plants along the margins

Temperament, diet & tankmates

Schooling: Shoaling; keep in groups of 6 or more
Diet: Omnivore; prepared foods with regular vegetable matter
Recommended tankmates: Similar-sized peaceful community fish — Similar size and water needs
Avoid keeping with: Much smaller fish — May outcompete or bully tiny tankmates

Breeding & notes

Sexual dimorphism: Males often slimmer and more colourful
Breeding method: Egg-scatterer; no parental care

Frequently asked questions

Is Moroko easy to keep?

A moderate-level species: mostly peaceful; some species nip fins; stable water matters more than fancy equipment.

What temperature and water chemistry does Moroko need?

Aim for 10–24 °C. Unheated for temperate species; 10–24 °C curated husbandry range.

How big does Moroko get, and what tank size?

Expect 5–8 cm as an adult, living middle of the water column. A 60 L tank or larger gives it room.

What does Moroko eat?

Omnivore; prepared foods with regular vegetable matter. Vary the menu — quality flakes or pellets plus frozen or live foods.

Can Moroko live with other fish?

Mostly peaceful; some species nip fins; shoaling; keep in groups of 6 or more. Good company: Similar-sized peaceful community fish — Similar size and water needs. Keep away from Much smaller fish — May outcompete or bully tiny tankmates.

Where does Moroko come from?

Native to Japan, where it lives in clear streams and rivers over gravel. Moderate, well-oxygenated current; Appreciates well-oxygenated water.

Does Moroko jump?

Not a noted jumper — a standard cover still keeps dust and spray in.

How does Moroko breed?

In the aquarium: egg-scatterer; no parental care. Males often slimmer and more colourful.