Harlequin Colours

Assuming they are the same species, they should change colour as they mature. However, there are a couple of reasons why they may not.

The two batches of fish will probably be from different breeders, and they may have each developed a slightly different colour strain. Like you can have white platies, red platies, yellow platies etc.

They may not both be Trigonostigma heteromorpha. But if this is the case, the black patch will be a different shape.

Thanks Sue. They are Trigonostigma heteromorpha I considered espeis and hengelis but decided on 'standard' Harlequins in the end. I did wonder about colour strain. I guess time will tell!

You never know what breeders do to make their fish 'prettier'. Feeding certain things to enhance colours is not unknown, then they leave the breeder, stop eating whatever it is and eventually loose the colour enhancement shortly after the fishkeeper has bought them.

I'd forgotten fcmf's comment on regional variation!