pale fish and flashing

Question
please help i have a 75 gallon cihlid tank and my dempsey is pale for a month now when he was i nice dark blue he is also flashing sometimes.water test is ok .i also see some other fish flashing sometimes but nothing visible, they all eat well.and i do weekly water change.my question is why is my 7inch dempsey pale?and flashing sometimes?

Answer
Chris,
Sounds like you might have a parasite in the tank. Make sure you check the fish out completely. Even shine a flashlight on them to check for velvet. If he has it you will see copper or gold looking "sand" on the fish. Keep the water very clean. You can treat with the heat/salt method and this will help he out a lot. This usually clears up any parasite problem, I ever have in the tank, which is not very often at all Saying the water tested ok is not the same as giving the readings. What are the levels of ammonia, nitrite, and nitrates in the tank. This is very important when keeping fish. After trying the heat/salt treatment, let me know how he is doing. If you need help with the treatment let me know.