keep loosing catfish

Question
I've recently lost 8 corydoras and 1 royal whiptail, for no obvious reason. Ihave a 40g planted aquarium with 3 blue discus 20 cardinals and a few algae shrimp. I did have 8 gold stripe corys and a whiptail, but the all died in the space of a week. All other fish are fine, I make 2 20% water changes a week(mixture of RO and conditioned water) my levels are Ph 6.3, Amm 0, No2 0, No3 6, GH 6, KH 11, temperature is about 28c. I noticed that one of the corys had little clear bubbles attached to its body. Is it possible that this 1 fish was infected and killed the rest???? Any possible answer would be greatly appreciated.
Dan.

Answer
Dan,

I saw no one had answered this yet and wanted to make sure you were getting the help you needed.  Unfortunately I don't have time to answer this at the moment, however here is a great forum dedicated to fish health and diseases that should help you:  http://www.aquaria.info/index.php?name=PNphpBB2&file=viewforum&f=67

Good luck with your fish!


Sean
Owner - FishGeeks.com