Boeseman's Rainbowfish Identification Guide

Key identification features

• Deep-bodied, laterally compressed shape typical of rainbowfish
• Mature males show a dramatic two-tone split: the front half of the body is blue-gray to purple, the rear half bright orange-yellow
• Females and juveniles are more uniformly silvery with a pale yellow wash and lack the sharp color division
• Two separate dorsal fins along the back
• A deeply forked tail fin, often tinged orange in males
• A steep, humped forehead profile that becomes more pronounced in mature males

Common look-alikes

• Other Melanotaenia rainbowfish: share the deep body and forked tail but lack the sharply divided two-tone coloring seen in mature Boeseman's males.
• Red rainbowfish: shows a fairly uniform red-orange body without any contrasting blue-purple front half.
• Turquoise rainbowfish: displays an even blue-green sheen across the whole body rather than a clean split into two colors.

Where you'll see one

Boeseman's rainbowfish are native to the Ayamaru Lakes region and connected slow streams in West Papua, Indonesia. They form loose schools in open water over vegetation, with males displaying their brightest colors during social interactions.