Strangly Behaving Fish

Question
Recently one of my tropical fish, a platy, had unusual white patches on it's body, and it's fin seemed to be rotting compared to others of it's kind. I treated the water correctly with anti finrot and fungus solution, but the fish still died. Since then, my other fish - mollies, tetras and harlequins, have been staying at the very surface of the water as though they're short of air. I've an oxygen pump working fine, but it isn't making a difference. I had to take the carbon filter out for the fungus medication to work - will this have anything to do with it? The tank is a Jewel, 54 litres - 4 harlequins, 1 molly, 1 platy, 8 cardinal tetras, one phantom tetra. pH, ammonia and nitrite levels all seem perfectly fine. I'm afraid to take off the tank lid as fish have before jumped out and died. They can't swim around for long without having to up to the surface again. Please Help, yours, Rachel Gibbons Horsham  

Answer
Hi Rachel;

It sounds more like a parasite, perhaps a gill parasite. Especially since your water chemistry seems okay. Make a 25% water change, using a good water conditioner to refresh the water and hopefully reduce some of them in the water itself. Here is info about what the possibilities and treatment options are;

http://www.nationalfishpharm.com/fish_diseases/gill_disorders.html
http://www.plantedtank.net/fishdiseases.html
http://www.thetropicaltank.co.uk/hdgilld.htm

If it isn't one of those, could a toxin have gotten into the water? Soap, detergent, hand lotion, etc. are a few possibilites. Water changes will help if you think it's possible. Do a 25% change every day for the next 4 or 5 days and see how it goes.

I hope they feel better soon.....

At Your Service;
Chris Robbins