Kota Kinabalu wet market is open at night, but the vendors use coloured lights to enhance the colours of the fish they're selling. It however makes it very unnatural and photos taken have very strong blue or red colour casts.

To fix this, I used Darktable's RGB Primaries module with instructions from this online tutorial by Boris Hajdukovic.

As a documentary and journalism photographer, I usually avoid creative editing that changes a photo heavily from the original, but this one is for learning so in addition to removing the colour cast, I also applied RawTherapee's Fuji Provia LUT and some changes in colour zones to get this specific look.

You can get a large amount open source LUTS all in one place from this Github repository.