Merlin has copper-colored eyes. I've never seen that before in a fish.
Anywho, My fishy pet peeve is:
Well, I'm not exactly sure if it's a pet peeve, as I'll pretty much buy any Betta.
I tend to buy the sickest, most pitiful fish I find.
I had to make a rule for myself so I don't get overloaded:
I can't buy another Betta unless all of my current fishies are healthy and situated habitat-wise. That way, (unless one of my healthy Bettas gets sick while another is healing) I'll only have one sick fish at a time.