Forktail Rainbowfish Identification Guide

Key identification features

• Very small, typically 1.5-2 inches (4-5 cm)
• Slender, semi-transparent body with a faint yellowish tint
• Bright iridescent blue eyes that give the group its "blue-eye" name
• Deeply forked tail with yellow lobes edged in black, more pronounced in males
• Elongated first dorsal fin rays in mature males
• Faint dusky midline stripe visible under close inspection despite the otherwise clear body

Common look-alikes

• Threadfin Rainbowfish: has trailing thread-like fin filaments this species lacks, though both are small and slender
• Celebes Rainbowfish: larger, more robust, and shows a blue-green body sheen rather than transparency
• Neon Rainbowfish: solidly colored neon-blue body rather than transparent with only the eyes and tail showing color

Where you'll see one

Native to slow coastal streams, swamps, and grassy pools of eastern Papua New Guinea, usually schooling in shallow, well-vegetated water. It stays close to the surface among reeds and floating plants, rarely venturing into deeper or fast-moving channels, and often shares habitat with other small native rainbowfish species.