Cairnsichthys is a genus of rainbowfishes from the subfamily Melanotaeniinae.

The genus is endemic to freshwater streams in eastern Queensland in north eastern Australia.

[2] The genus was designated as a monotypic genus in 1928 by John T. Nichols and Henry C. Raven but in 2018 a second species was assigned to the genus.

[3][4] The genus is named after the Australian city of Cairns with the suffix ichthys which is Greek for "fish".

[6]