African Cichlids fish disease

Question
I have 4 African cichlids in a 25 gallon tank.  Recently I noticed one of them hanging around the bottom.  It only swims with the 2 front fins and keeps his tail fin closed up.  Because the tail is closed shut, I can't tell if the fin is actually rotting away or not. I cleaned the tank after noticing the fish acting strange. 1/3 water change.It has been 3 days now, and he swims with his head up and tail fin pointed down.  Still able to eat good.  Catches food floating to the bottom.  No signs of cotton like fungus, or sugar like grains anywhere.  Pet store tested my water.  Said PH was quite low.  Recommended I add crushed coral to tank.  I have done that, it has been 1 day since and the only difference I noticed is that the fish now seems to be scraping himself against the rocks. There only seems to be the 1 fish affected.  What should I do next?

Answer
Hi Mingo,
Poor fish. The sad thing is its very hard to diagnose any fish without getting a good look at it and even then, sometimes the use of a microscope and viewing a scraping sample of the affected fish is the only way to properly diagnose.

Does your water naturally have a low pH? Test your tap water to see. If it is naturally low you may or may not have to adjust it. Crushed coral is a great way to add minerals to the water and help raise the pH. Sometimes its not always necessary to have to raise your pH as long as its not in the extremes. If your other African cichlids are doing well then I don't know if I'd really try to change the chemistry.

It's possible you may have a low pH due to water that hasn't been changed frequent enough. Dissolved organics will naturally release acid and therefor lower your pH. So all that would be needed in a case like this is to change the water extra and make sure to gravel vacuum thoroughly.

Really all I'd recommend for now is to start changing 30-50% of the tank water everyday on your cichlid tank, for the sake of the sick one. Sometimes clean water is the best treatment for sickly fish. Often it will help what medications simply won't.

I hope this helps!
Karen~