Fish ID - Brass Tetras?

[BeckyCats]

Hello. Both of these were sold to me (separately) as brass tetras, but they look a bit different. One has one shiny spot on his head and the other has a shiny stripe down his body. I have attached pictures although the larger (head-spot one) is always blurry in photos. Are both of these brass tetras? (By the way, I know they want to be in larger groups, but I cant find any. I'm trying to build up their numbers but so far these 2 are all I've found.)

 

[Byron]

It might help to first identify the species. "Brass" Tetra turns up two fish, the African species Alestes humilis, and the South American species Hemigrammus rodwayi which is often seen as "Gold" Tetra. In the photos above, the white/blue tips to the fins initially suggested the Silvertip Tetra, Hasemania nana, to me.

It is always possible that a species is being developed into a variety, and coupled with the new species entering the hobby (many of which have not even been described yet), identifying some can be tricky.

One comment on the Gold Tetra...an interesting fish because of its golden colouring, giving the impression of having been dusted with gold powder. This is actually guanin secreted by the fish as a protection against a parasite that occurs in its habitat waters, and only wild-caught fish have this colouration. Tank-raised fish do not develop the golden colouring but are a grey-silver. The accompanying photos illustrate the wild golden fish (first photo) and the grey-silver colouration of tank raised fish (second photo). I'm also adding a photo of the African fish, though having never seen this species I cannot say how much if any variation may occur among individuals or populations.