ok..so i have a common goldfish about 5 inchs long....and for a little while he is being losing scales and also now i noticed that he is missing two little chunchs of the end of his tail..is this fin rot?? he is being like hiding and not really active for a couple of days and i dont want him to die...what could be a good treatment if it was fin rot?....i dont have quarantine tank but i have a big bucket with an air pump..would that work or should i just put the treatment in my 75 gal? i have a pleco and three more shubunkin goldfish.