Why are my wierd fish....?

it is hard to answer this questions without knowing the size of the tank, how long it has been running, what the fish are ??? it sounds to me like a water quality issue but it is really impossible to answer this question without more information ... like how was the tank cycled ... is the tank large enough for goldfish ... are the goldfish at the right temperature or are the small fish at the right temperature ... how has the tank been cleaned and maintained ... like, you do not even know the size of the tank ?!!?