Hainan Horse-Mouth (Opsariichthys hainanensis)

Family: Cyprinidae

Hainan Horse-Mouth — a Cyprinidae from China, mostly peaceful community fish. Reaches 7.9–11.7 cm; singly or in small groups depending on temperament. 10–20 °C.

Care parameters

Water temperature: 10–20 °C
pH: 6.5–7.5
GH hardness: 5–15 dGH
Adult length: 7.9–11.7 cm
Minimum tank: 164 L
Water layer: Bottom-dwelling
Difficulty: Moderate
Temperament: Mostly peaceful community fish
Origin: China

Species overview

Opsariichthys hainanensis is a Cyprinidae from China. In the wild it prefers clear streams and rivers over gravel; in the aquarium it stays mostly peaceful community fish. Plan on 7.9–11.7 cm of adult fish at 10–20 °C. Related profiles: Opsariichthys bidens, Opsariichthys pachycephalus, Opsariichthys evolans.

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: Singly or in small groups depending on temperament
Diet: Accepts quality flakes, granules and frozen foods
Recommended tankmates: Similar-sized peaceful community fish — Compatible size and temperament
Avoid keeping with: Fin-nippers — Constant stress

Breeding & notes

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

Frequently asked questions

Is Hainan Horse-Mouth easy to keep?

A moderate-level species: mostly peaceful community fish; stable water matters more than fancy equipment.

What temperature and water chemistry does Hainan Horse-Mouth need?

Aim for 10–20 °C. Room temperature to heated, depending on origin; 10.0–20.0 °C typical for the genus.

How big does Hainan Horse-Mouth get, and what tank size?

Adults reach 7.9–11.7 cm; it is bottom-dwelling. Plan for at least 164 litres.

What does Hainan Horse-Mouth eat?

Accepts quality flakes, granules and frozen foods. Vary the menu — quality flakes or pellets plus frozen or live foods.

Can Hainan Horse-Mouth live with other fish?

Yes, with care. Mostly peaceful community fish — pair it with Similar-sized peaceful community fish — Compatible size and temperament and skip Fin-nippers — Constant stress.

Where does Hainan Horse-Mouth come from?

Comes from China: clear streams and rivers over gravel. Expect moderate, well-oxygenated current and appreciates well-oxygenated water.

Does Hainan Horse-Mouth jump?

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

How does Hainan Horse-Mouth breed?

Egg-scatterer; no parental care. Males often slimmer and more colourful.