Help fish just swim and swim madly.

[MagickFish]

One of my fish just swim and swim and swim around and around and around, normaly he is reserved and like to sit near the surface and is not wery active nor frindly whit other fish, now he swim like an idiot and dont stop and I am getting worrid. He do eat though. What can be wrong whit him?

[William]

What species is it.

[MagickFish]

I have no idea. he is 3 and a half cm long, see though silvery of color, his tail have a triangular black sput and his fins, incloding back fin are readish, and he is insane.

[MagickFish]

He was a (saksefisk) sissor fish? I think, he swam around madly for several days but then sadly he died. I wonder what was wrong whit him.