I think my paradise fish is sick

Question
I had a paradise fish for about 2 years. He was given by a friend, and he was already an adult paradise fish when i had him.

In the past week he had been acting weird. He doesn't move as active as in the past (he used to swim really fast when I fed him and the other fishes). Now, sometime he just ignored the food. There are a few times that I noticed he is floating of -45 angle from the surface of water.... I changed the water (only 1/5 new water) but it is even worse... and the problem is the other fishes (not paradise fish type) in the tank have no problem... If it is the problem of the water, don't all the fishes have the same reaction?

I am very worried. Can you please help? Thank you very much!

Answer
Hi Jeff,
Its always possible it could be the water quality. And some fish are simply stronger then others and water quality issues affect them sooner then other individuals.

He could be getting old too. Not that I'm confirming this as the reason. Its always a possibility. Lifespan of the average Paradise fish is a few years.

I am wondering if he has a swim bladder problem. This can be very common type of problem with bettas (their close relatives) and many other types of fish.

The swim bladder is an organ that controls the fishes equilibrium. If something goes wrong, the fish will be quite disoriented and some even floating upside down uncontrollably near the surface. There are varying levels of severity. And several things that can trigger swim bladder such as intestinal blockage, bacterial infections in the swim bladder, kidney problems, tumors, cysts, and even some viruses.

But the most common type of swim bladder is that caused by diet. Often too much food at once or not enough fiber in the diet. Intestinal impaction will put pressure on the swim bladder. And the best treatment is to fast the fish for at least an entire day. Then offer a piece of a mashed pea to the fish. Sometimes feeding it on the end of a blunt toothpick works better than just dropping it in.
Some fish refuse peas, while others love them.
Alternatives to peas are frozen daphnia and brine shrimp.

Only feed the peas or daphnia/brine shrimp for a while to the paradise fish and notice if you see any change and pay attention to if his belly seems swollen or anything else odd.

Testing the water for ammonia, nitrites, and nitrates never hurts. Just in case.

As you know these levels should be as follows-

Ammonia-0 Nitrites-0 Nitrates- 20 or less

I do hope this helps and best of luck!
Karen~