Source: Boeseman's rainbowfish - Wikipedia

Boeseman's rainbowfish (Melanotaenia boesemani), also known as the Boesemani rainbowfish, is a species of fish in the family Melanotaeniidae.

M. boesemani is also available in the aquarium hobby, where it is prized for its excellent colours and peaceful demeanor. The colour pattern is completely different from most other forms of rainbowfish, as it has a half orange-red rear and a bluish-grey or purple front which in some specimens is almost defined perfectly. M. boesemani will often grow to lengths that exceed 10 cm (3.9 in) if given the right food and water conditions. Like most rainbowfish they are capable of adjusting their color intensity. Their color intensity may be a sign of mood or health. Generally more intense is seen during night time. They are kept best in groups (with as much as or more females than males) due to their community and friendly nature and can be easily kept with many different species of fish, including some tetras. They are a relatively hardy fish that prefer weakly alkaline pH conditions. Good tank mates include other rainbowfish, barbs, tetras, corydoras, snails, gouramis, danios, discus, guppies, swordtails, and loaches. However, smaller freshwater shrimps in the genera Caridina and Neocaridina may be viewed as prey. Ghost shrimp, vampire shrimp, amano shrimp and bamboo shrimp can live with them. Always adult shrimps are added first then baby rainbowfish. Care must be taken to give hiding places for shrimp and open spaces for rainbowfish.