Boesemani Rainbow
Boesemani Rainbow (Melanotaenia boesemani) is one of the most spectacular freshwater fish available anywhere in the hobby. The front half of the body is a deep, iridescent blue-grey to violet, while the rear half transitions dramatically to vivid orange-yellow — a two-tone color split that is bold, graphic, and instantly recognizable. Named for Dutch ichthyologist M. Boeseman, this fish is the flagship species of the rainbowfish hobby.
Feeding & Care Tip: Sera Vipan Tropical Flakes and Hikari Micro Pellets make excellent daily staples — crush flakes for juveniles and soak pellets to prevent bloating. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Bloodworms to enhance the vivid orange-and-blue coloration. Feed small amounts 2–3 times daily. Rainbowfish are fast, competitive eaters — ensure all fish get adequate food.
Native to the Ajamaru Lakes system in the Bird's Head Peninsula of West Papua, Indonesia, the Boesemani Rainbow is now Endangered in the wild due to water extraction and habitat alteration. Virtually all fish in the trade are captive-bred, making aquarium populations genuinely important for the species' long-term survival. In the aquarium, slightly hard, alkaline water replicates the limestone-influenced lake conditions of its native habitat.
Keep in groups of at least six with a mix of males and females. Males in a group display to one another almost constantly — the iridescent forehead stripe flashes brilliantly, the blue and orange colors intensify, and the fish fan their fins in competition. The display behavior is most spectacular when males outnumber females slightly. 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 — mixed sexes for best male display |
| Ideal Temp | 77–86°F (25–30°C) |
| Ideal pH | 6.5–7.5 |
| Ideal GH | 10–20 dGH |
| Ideal KH | 6–12 dKH |
| Staple Food | Sera Vipan Tropical Flakes; Hikari Micro Pellets |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Bloodworms |
| Origin | Ajamaru Lakes, Bird's Head Peninsula, West Papua, Indonesia |
| Notes | Endangered in the wild — aquarium stock is captive-bred. Slightly hard alkaline water preferred, reflecting limestone lake origin. Most iconic rainbowfish. Males display spectacular blue-orange two-tone split. Group of 6+ with mixed sexes essential. |
