elmo

Question
Hi Lynda,

Elmo is in a 4'x 18" x18" tank.

We feed him blood worm, pellets live crickets, live grass hoppers & brine.

every 2 weeks we do a water change between 1/4 - 1/3 of the tank.

he still swimming normally and eating except big swollen belly. I can e-mail you a picture if you require

thanks

Kylie

Answer
Hi Kylie,
I asked for the size of your tank because Oscars need lots of room to be healthy and happy.  One Oscar needs a 60 gallon tank, Two, you must double that.  
There could be one of two things wrong with him.  One is that kept in a tank too small, his growth was stunted, therefore not allowing his internal organs to grow.  When this happens, there is no medication, and eventually the fish dies.  Vendors never tell people this because they would never sell Oscars.  The Oscar is one of the most mistreated fish on the market through no fault of the buyer, but the vendor who is there just to make a buck.
This said, it could also be Swim Bladder Disease.  Swim Bladder is due to constipation, and poor diet which eventually lead to SBD.  Since he is still eating, feed him cooked frozen peas with the outer layer removed.  Feed him only the peas so that he can clean out his system.  Feed him nothing else for two days.  He must waste.  He should get peas one day every week, and on that day feed him nothing else.
I wouldn't feed him grasshoppers.  Crickets, and other insects bought at the pet store are very good for him.  You can also buy him worms at the bait store.  Clean the worms by leaving them in oats for a week or so.  It is good to feed him worms now, and then.  Minnows that you find at the bait store are also very good for him.  Green beans, carrots, broccoli, peas that you find at the market in the frozen section should be part of his diet.  Blanch them first.  You can also feed him bananas, mangoes, and apples to vary.  Frozen fish that you find at the market that come from rivers, and lakes is also good food for him.  Unfreeze the fish before giving it to him.  Do not feed him salt water fish.  Never feed him feeder fish.  Feeders have no nutritional value, and are sometimes full of disease.  The pellets that you are giving him are also very good for him, but soak them first as they are hard to digest.  Brine Shrimp, Bloodworms, and other frozen foods that you find at your pet store are also good.  A good quality flake is a "Must."
His water should be changed 25% every week without fail.  Test your water to see if it has ammonia, nitrites, or nitrates in it.
Ammonia should be zero, nitrites zero, and nitrates should be low.  Ammonia is the number one killer of fish, so it is important to do water changes every week.  If you have ammonia or nitrites in your water, you will have to do water changes everyday to get rid of it.
Hope this helps
Lynda