Threadfin rainbowfish

Iriatherina werneri

Males display a fan-shaped dorsal fin and trailing rays; their tiny mouths make feeding competition important.

Adult length: About 3 cm (standard length, without the tail fin)
Water temperature: 25–29 °C
pH: 6–8
Hardness: 5–12 dGH

Natural habitat: Inhabits lowland swamps, ditches, creeks and billabongs, especially densely vegetated margins with water lilies and other aquatic plants.

Keep at 25–29°C. Read group size together with swimming space.

Appearance and identification

A fan-shaped first dorsal is followed by elongated second-dorsal and anal rays. Females have shorter fins. Compare with the spotted blue-eye: the adult male threadfin's trailing dorsal and anal rays differ from its broad spotted fins.

Same-species behaviour

Keep at least six.

Space requirements

Use an aquarium 60cm or longer.

Diet and feeding

Provide very small food. Strong feeding competitors or fish that chase and nip long fins can create problems.

Compatibility limits

Avoid strong feeding competitors and fish that chase and nip long fins.

Sources