Fin splitting and not eating

Question
Hi. I have two oscars in my tank and one of them is shedding scales, barely eating, and it's fins are splitting in several places. Any idea on what's wrong or how to fix it?

55 gallon tank
2 oscars
1 flower horn
1 shark

pH and ammonia is good

Thanks,
Carol

Answer
Carol,

    First off your tank is too small for the amount of fish you have in it. Your 2 Oscars need to be in at least 70 gallons. When you say your Ph and ammonia are good, what does that mean? Ammonia and nitrites should be at zero at all times and nitrates no more than 20 ppm. If your fish is losing his scales it is usually a sign of bad water quality and not being fed properly. What are you feeding them? Oscars need to be in perfect water conditions at all times. You mention a shark in the tank but not what kind it is. Your shark, depending on the breed, could be attacking the Oscar. I would remove the Oscar form the main tank and place him in your hospital tank. He might also be suffering from fin rot. Any medication for it found at your LFS will help you out with that. Remember to always follow the directions on all medicine bottles. Never add more or less of the medication unless it says to on the bottle. Once you have removed the sick fish he might start feeling better. Good luck and if things change let me know.