has anyone ever seen this before? my 6 year old oscar has a strange growth on his butt..sometimes its huge and other times it looks as if it deflated...Looks like a blister???....pleace help...hes acting verry shy and hardly eats....

yes, I have heard of this before. Some people talk about the fish having a poleaxed rectum. It could also be haemorrhoids, silly it may seem, but I believe fish can get them

well.. any clue on how to treat it?..some fish preperation-h perhaps?

I am only surmising, it might be something completely different. When I read your post, it reminded me of something I read a while ago. I wouldn't have thought there is much you can do for a prolaxed rectum in a fish, there isn't much you can do for a human apparently. Since you're dealing with the digestive system, feeding a healthy diet is always very important. However, if this isn't affecting your fish, I shouldn't worry yourself too much.

humm...well...some days its horrable looking, like a 2-3 inch baloon off his butt, and other days it looks like a deflated bunch of skin....its wierd...oh and his stomach is kinda bloated around the affected area..i know the water is healthy, and the tank is clean....none of the other fish are affected ( i have a little oscar and a pleco in the same tank) im going to try to post a pic of it....thanks for the help.

If you feed dry food or meat a lot try to add insects to the diet, worms,crickets, mealworm,bloodworm etc as these will pass through the system easy and may help