Lake Kutubu rainbowfish

The lake Kutubu rainbowfish is found in a very small range at 800 metres above sea level in Papua New Guinea, specifically in Lake Kutubu and the Soro River.

Depending on its diet, as well as water parameters, the lake Kutubu rainbowfish can display a range of different colours and patterns. These range from cobalt blue through steel blue and aquamarine to lighter and darker shades of turquoise.

The males are more strikingly coloured and larger than the females. Males can reach a maximum length of 12 cm. 

The male initiates the courtship display. During this period, his plumage takes on particularly vivid colours. The area around his neck turns a bright orange or golden colour.

When the male encounters a female ready to spawn, the pair swim amongst denser plants. Both fish then position themselves parallel to one another, begin to tremble, and the female releases her eggs. The male immediately fertilises the eggs.

Over the course of several days, the female lays around 40 to 100 eggs. These have a maximum diameter of 2 mm. The young fish larvae hatch after a few days to two weeks. They do not reach full size until 1.5 years later.