Steel-blue Killifish Identification Guide

Key identification features

• Compact, cylindrical body rarely over 5-6 cm, typical of pond-dwelling annual and semi-annual killifishes
• Overall body color is a cool metallic steel-blue to slate-grey, brightest along the upper flanks
• Fins often show a subtle iridescent sheen with fine reddish or brown flecking near the edges
• Males have extended, pointed or lyre-shaped dorsal, anal, and caudal fin tips; females have short, rounded fins
• Flattened top of the head and an upturned mouth positioned for snapping insects from the surface film
• Faint rows of dark spots may run along the midline, more visible in bright side lighting

Common look-alikes

• Rachovi killifish: has strong red-orange banding rather than an overall cool blue-grey tone
• Chocolate Australe: shares a similar lyretail fin shape but is warm brown to gold rather than steel-blue
• Palon killifish: smaller-finned and lacks the pronounced lyretail extensions on the caudal fin

Where you'll see one

Found in shallow forest streams, seepages, and temporary pools across West Africa, where dense leaf litter and shade keep water cool and tannin-stained. It tolerates soft, acidic water and is most active near the surface at dawn and dusk when insects fall onto the water.