Turquoise Rainbow
Turquoise Rainbow (Melanotaenia lacustris) — also known as the Lake Kutubu Rainbowfish — is one of the most intensely blue rainbowfish available. Males develop an extraordinary deep turquoise to teal body color that shifts between blue and blue-green depending on the light angle. The body color is more uniform and consistently saturated than most rainbowfish — there is no dramatic two-tone split, just an unbroken expanse of electric blue.
Feeding & Care Tip: Sera Vipan Tropical Flakes and Hikari Micro Pellets make excellent daily staples. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Bloodworms to maintain the intense turquoise coloration. Crush flakes for juveniles; soak pellets.
Native exclusively to Lake Kutubu and its outflow river in the Southern Highlands of Papua New Guinea — an isolated, pristine highland lake with notably clear, alkaline water. The distinctive turquoise coloration is most vivid in slightly hard, alkaline conditions that replicate the mineral-rich lake water of its origin.
Keep in groups of at least six with mixed sexes. Males display actively to one another with color intensification and fin displays. The blue coloration deepens noticeably when males are competing. Completely peaceful with other medium to large community fish.
A well-planted aquarium with open swimming space in the center replicates the rainbowfish's natural riverine habitat. These are active, fast-swimming fish that appreciate length more than height — a longer tank allows them to build up speed and display properly. Good filtration and regular partial water changes are important, as rainbowfish are sensitive to deteriorating water quality. Avoid very small or slow-moving tankmates that may be outcompeted at feeding time.
Care & Ideal Parameters
| Difficulty | Easy |
| Temperament | Peaceful — Community |
| Typical Adult Size | 4.5 inches (11 cm) |
| Min. Group Size | 6 minimum — male competition deepens blue color |
| Ideal Temp | 72–82°F (22–28°C) |
| Ideal pH | 7.0–8.0 |
| Ideal GH | 10–20 dGH |
| Ideal KH | 5–12 dKH |
| Staple Food | Sera Vipan Tropical Flakes; Hikari Micro Pellets |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Bloodworms |
| Origin | Lake Kutubu, Southern Highlands, Papua New Guinea |
| Notes | Also called Lake Kutubu Rainbowfish. Intense turquoise-blue is unique among rainbowfish — most vivid in slightly hard alkaline water. Endemic to Lake Kutubu. One of the most beautiful blue freshwater fish available. |
