I want to say male? Someone correct me if I am wrong. Females are silver and smaller than the males. The one looks full grown and has red to him. Also, it may be nothing, but I think I see white stringy feces. That could be internal parasites. BUT, sometime that can be just what you fed them. But if that is everyday and continues to look stringy, I would look into what is wrong. That may be why he is a little pale. And how big is that tank?