Help, I have lost six fish in 2 days!

Ill get a test kit in the morning, for tonight Ill do a 40% water change or is that to much?
 
Its a liquid drip test, Im sure I cycled ok, added the cardinals first, after 2 weeks, then the rummynose. Did it all slowly, I havnt added any fish in the last six weeks and the nitrite levels have always been low, Why would an ammonia problem suddenly develop. Would this cause fish to bloat? Could it be something to do with overfeeding. I do have to put alot of bloodworm in to make sure the frogs eat, the fish always grab it. The fish are ALWAYS hungry!!


Overfeeding is a major cause of elevated ammonia levels. Anything decaying in the tank, food, dead fish, etc, will elevate ammonia levels..is all of the bloodworm always eaten?
 
I am having a simialr problem in my tank! I bought some Rasbora and have been losing about one a day. A couple were bloated, but not pineconed, a couple had milky eyes before dieing, one had protrudung eyes, and a couple looked totally normal (one was kind of gasping before he died). I have been testing repeatedly and have 0 nitrites,
0 amonia and nitrates are 10. Maybe we have the same problem. I bought
Maracyn Two but have not used it yet because I have never done so before and I am unsure if I should or not.
 
AquariaCentral.com