hello and welcome :)
perhaps someone will be able to move this for you,as you
will hopefully get the answers you will need.
if you can let people know more about your fish,it will help people
to help you,i know it's distressing at the moment,however..........
what size tank is he in.
what temperature is the tank kept at.
water changes,how much, and is dechlorinator added.
as many things as you can think of please.