I have had my oscar for 5 years now. He resides in a 150 gallon tank. He is about 12 to 13 inches long and 2 1/2 to 3 inches at his widest area. My concern is that lately he has become VERY VERY swollen in his abdominal region. His anus is also extremely swollen. He sits on the bottom of the tank and has become lethargic. He is not as active as he was a couple weeks ago. He used to chase the other fish around (2 smaller oscars, a Jack Dempsey, and a pleco) and now he isnt even doing that. I have no idea what could be wrong. The tank is taken care of very well and he has never been in this state before. Any info would help me. I do not want to lose this fish. He is a member of the family.

what are you feeding your oscar on

I think dinger has constipation on his mind

The fact that the anus is swollen does sometimes point to constipation. Sometimes vegetables such as peas are recommended as food when this happens. Unfortunately, if the Oscar isn't eating, it obviously isn't going to work. A few years ago I had something similar to this, my red Oscars anus became very swollen and after a couple of days, she passed the most enormous turd I have ever seen. I swear it was almost as thick as my little finger. However I don't remember her abdomen becoming swollen. Do you know if it's a male or female, and if so, have you ever seen eggs being laid before? Never had it myself, but I know fish can sometimes become egg bound. Since the female Oscar will become quite distended when she has legs, this is also a possibility. Probably a remote possibility, but something to think about. Oscars do stop eating when they are about to breed.

The fact that your Oscar isn't eating isn't a very good sign am afraid. When fish stop eating, that means they aren't feeling very well. This could be due to the fish feeling very uncomfortable, or it could mean that she's feeling very ill, very difficult to say at the moment.

Can you possibly post some photographs? Also test the water for ammonia, nitrite and nitrate, do the ph as well.

What is the fish is breathing like, is he opening and closing his mouth constantly?

Anyway, don't want to overload you with questions, get back when you can

The Ph level is normal so are the nitrates and so on. I am not sure if this fish is female or male even though I have had it for 5 years. I noticed there were some eggs laid on a flat rock in the tank a couple weeks ago and then the next morning they were gone. I believe that is when this fish started getting swollen. It is constantly opening and closing its mouth and I am afraid today things dont look any better than yesterday. I feed it mainly pellets and give them peas and some shrimp that I cut into pieces. I was breeding convicts to feed them but the male convict killed the female after the last batch of babies.

My fish dosent come up to the glass and "play" anymore. Just sits on the bottom of the tank.

We also feed them crickets and worms that my kids drag in from the yard.

Your situation doesn't sound good. Fish open and close their mouths in these situations for various reasons. It could be extremely stressed because of the condition, it could also be gasping for oxygen because it is ill. Have you checked the oxygen levels in the aquarium, is the filtration agitating the surface area of the water? Unfortunately, I've had fish in this situation before, I've lost them every time. I have tried medication for internal bacteria infections but they haven't worked. The best you can do at the moment is to regular water changes and keep the water in extremely good condition. Don't keep putting food in for the Oscar if it won't eat. I'm sorry I can't be any more help for, like I said, I've seen fish like that before and unfortunately, they haven't survived. I could be totally wrong, your fish might pull through, let's hope so. The swollen abdomen could be a number of things, I doubt its eggs, it could be worms in the intestine, or it could be a bacteria internal infection. The fact that it isn't eating does ring alarm bells.

Just keep an eye situation, if you oscar is still doing this in two or three days, come and tell us and we can try and advise where you can go from. There is always the vet, he may be on to prescribe something.

Im not sure, but sounds like your fish may be suffering from constipation. I have seen this before in peoples Oscars that i have been asked to look at. if you are feeding pellets to your Oscar regularly i think this may be the cause. I am not a lover of pellets in fact i havn't fed pellets for years and have always advised against them. I have used several ways that have been succesful which you may wish to try. Firstly if your oscar is eating try feeding it solely on live food worms are great.
If your Oscar doesn't feed like it normally does then starve it for a few days. Don't worry it wont starve after a few days. The most radical method i have used is to remove the fish from the water and spoon a small amount of castor oil into its mouth. This is not as hard as it sounds. You can remove the Oscar in a net and place it in a wet towel. once the Oscar is totally covered it should stop moving . Carefully open its mouth and put some castor oil in about a third of a teaspoon. This method is not for the fainthearted and should only be used as a last resort. You could try soaking food in the castor oil but obviously not live food.If your fish recovers try to avoid pellets.

Much to my dismay, my oscar, Mr.Blonde, has died. I pretty much knew that was going to happen. I just want to thank everyone who posted advice for me. If I would have had more time I would have utilized some of your suggestions. Again, thanks so much for your advice. I am glad that this site is available for people who truly enjoy their oscars.

really sorry to hear about your Oscar. Unfortunately, I think he was too far gone to save. Fish are really difficult to treat sometimes. Anyway, don't give up on them, they are wonderful fish.