Bully Goldfish
I have 2 goldfish in a 26-28 litre tank. They've lived quite peacefully up until now. But now Alan won't stop chasing Maddy and it's driving us both insane.
They're of similar size, although I'd say Maddy has a slightly larger body while Alan has longer fins. He chases her constantly, absolutely relentlessly, from first light until they settle down behind their bridge together at night. He also pecks at her eyes and I can't find out why ANYWHERE online. I've treated the tank with Methylene Blue incase she had something tasty growing on her that I couldn't see. The water is kept clean, I change 25% every 2 days, clean the gravel, treat it with nitrate clearer and chlorine remover, they have a good air supply. Nice plastic plants to hide in. They get handfed so I know how much they get each. They're spoilt fish. It would be nice if Alan could for once appear grateful, happy, and content with his lot.
My theories are:
Sexual, although I've heard this behaviour only happens in spring?
A parasite or disease I can't see (I have some disease treatment on the way to me just incase).
Getting a third fish? Theory being he can't bully 2 fish the same as he can 1.
Competition for food? If he sees her pecking at gravel he's over there straight away moving her out his way. I don't really want to feed them more than I do, it's not good for the water.
Or is he just a vindictive bully by nature destined to drive Maddy to an early watery grave? I can't house them seperately, no room.
Any suggestions or solutions GRATEFULLY recieved!