swimming vertical

Afternoon all, As of this morning one of my guppies in the 87l tank has started swimming almost vertically, tail down, mostly in the corner of the tank but sometimes out in the middle. He seems capable of swimming normally. If one of the other fish comes over and gives him a nudge, he'll set...

I just took over our tank. Think it's a 10gal, maybe 15. We have a cheetha patterned goldfish (think it's a goldfish) that has some scales missing and is swimming vertically, sometimes upside down. This began several days ago. We also have some kind of japenese yellow sucker (bottom feeder...