Turquoise Rainbowfish

Native to Lake Kutubu in Papua New Guinea, one of the most isolated and pristine lakes on the planet, this rainbowfish carries some of that clarity in its coloring. Adults develop a striking turquoise-blue that shimmers along the flanks, often deepening toward the dorsal area while the belly takes on a yellowish or pinkish cast. Males are the showstoppers, their color intensifying dramatically when rivals or females are nearby. Females are subtler but still attractive fish worth keeping.

At around 12-13 cm fully grown, these are among the larger rainbowfish you'll encounter in the hobby. They need horizontal swimming space more than depth, so long tanks work better than tall ones. Water should lean alkaline, somewhere in the 7.2 to 8.0 range with moderate hardness, which actually makes them a decent fit for many tap water conditions in harder water areas. Temperature flexibility is a strength here: anywhere from 22 to 28 degrees suits them well.

Feeding is straightforward. They take high-quality flake, pellets, and frozen foods enthusiastically, and occasional vegetable matter rounds out their diet nicely. Don't skip the variety though, fish fed only flake never develop the color depth they're capable of.

They're genuinely peaceful toward other species and rarely cause problems in a community setup. A group of six or more swimming under good lighting in a planted tank is one of the more impressive sights in the freshwater hobby. Color, size, and movement all come together.

If you want to see how other hobbyists have used these fish, browse through community tank builds featuring Melanotaenia lacustris for some real inspiration.