[5] This study separated M. splendida fluviatilis into two species, M. duboulayi from the coastal river systems east of the Great Dividing Range in northeastern New South Wales and southeastern Queensland, and M. fluviatilis from the inland Murray-Darling basin system west of the Great Dividing Range.

The larger males are distinguished from females by their brighter colours and can be identified from the elongation of posterior rays in the second dorsal and anal fins.

Spawning occurs prior to summer rains, and the eggs adhere to filamentous subsurface vegetation and floating plant roots.

[7] Crimson-spotted rainbowfish were favorably described by Castelnau in his initial description: "...He says the colours during life were most beautiful; that a broad stripe of magnificent blue ran along the sides, and two transverse bands of rich scarlet extended on the upper part of the fish towards the middle of the body.

In their native range, they are also released into Australian dams to control mosquitoes using local wild stock to prevent endemic variants of M.duboulayi from being lost by genetic contamination from non-local forms.