Sepik Rainbowfish Identification Guide
How to recognize the olive-toned Sepik Rainbowfish of Papua New Guinea's Sepik River system.
Read the full Sepik Rainbowfish encyclopedia entry →
Key identification features
- Moderately deep, compressed body typical of rainbowfishes
- Olive-green to bluish back with silvery-yellow flanks
- Faint dark midlateral stripe broken into short dashes or spots
- Two dorsal fins, often washed with yellow or pale orange
- Males more intensely colored than females, with slightly longer fin rays
- Moderately large eyes and a gently sloping forehead
- Rounded caudal fin with faint darker margins
- Grows to about 8-11 cm
Common look-alikes
- Parkinson's rainbowfish: shows more reddish fin coloration and comes from a different, southeastern river system.
- Lacustrine rainbowfish: solid vivid blue coloration versus the more olive tones here, and restricted to a single lake rather than a river system.
- Emerald rainbowfish: deeper-bodied with a pronounced humped nape in males, which this species lacks.
Where you'll see one
Inhabits the Sepik River drainage and its associated floodplain lagoons and tributaries in northern Papua New Guinea, favoring slow, vegetated backwaters and quiet oxbow lakes away from the main river current and heavy sediment load.
Frequently asked questions
How do I know a rainbowfish from the Sepik system isn't a lacustrine rainbowfish?
Lacustrine rainbowfish are restricted to a single lake and show solid vivid blue color, while Sepik rainbowfish are more olive-toned and come from river and floodplain habitat.
What fin feature helps confirm a Sepik rainbowfish?
Look for two dorsal fins washed with yellow to pale orange rather than strong red, which points away from Parkinson's rainbowfish.