Pale Oscar

Question
I have 2 Tiger Oscars I purchased approximately 1 month ago.  They are about 3 inches long and are in a 15 gallon tank.  I do plan to set up my 75 gallon tank soon to move them into.  Both fish seem very happy so far but since day one, one of the fish has been much lighter in color than the other and seems pale.  In the past few days it appears as if it's eyes are starting to protrude (possible start of pop eye).  Water levels all seem normal but the water does seem to be getting cloudy.  I do weekly 25% water changes.  Tank is actually about 8 months running and does have a pleco in it.  All fish seem to get along fine.  Do I need to worry or should I treat with something?

Answer
Hi Chris;

Make more frequent water changes. I would vacuum the gravel once a week while removing 25% of the water. Until you get them to a bigger tank you might want to do the water changes twice a week. Oscars are very messy deep-bodied fish. They need lots of room.

If he is developing an infection inside his body, he may need antibiotics. Kanacyn by Aquatronics and Maracyn 2 by Mardel are two that will get inside the fish to treat such infections. Raise the temperature to 80 and add extra oxygen to the water with the use of an air pump and air stone. The elevated temperature helps kill bacteria and speed up metabolism of the fish, and the oxygen makes up for the fact that warmer water carries less oxygen.

Internal infection isn't the only cause of the symptoms as you are describing. The other possible causes are incurable and include cancer, organ failure and internal physical deformity. Just keep up with the water changes to get him immune system in tip-top shape. They need a bigger tank as soon as possible.

Followups welcome

At Your Service;
Chris Robbins

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