OP, you said "parameters are ammonia 0 nitrites .25 nitrates 20", which reads to me that you tested the water after the die off. If that's the case than your test provided false readings - since 0 ammonia in a tank with a handful of dead fish is next to impossible. So, what chemicals are you using in your tank that provided the false reading?
If all of that is true, than you were getting false readings for a while. The new fish was the first to die, from Ammonia poisoning (like maybe he came from a clean tank and went into the high ammo tank and it shocked him to death). The additional ammonia released from his dead body killed everyone else (they may have been close to the tipping point anyway). Did you notice, at any point from Sunday to Tuesday that the other fish were hanging at the bottom of the tank? This would indicate a higher-than-they're-used-to ammonia.
If your water is as jacked up as it appears to be, the amount of bio-balls you're using is not sufficient. I would recommend you switch to pond matrix and pot scrubbies in the canister, this mix is several dozen times as effective as bio balls.
Good luck, that definately sucks.
If all of that is true, than you were getting false readings for a while. The new fish was the first to die, from Ammonia poisoning (like maybe he came from a clean tank and went into the high ammo tank and it shocked him to death). The additional ammonia released from his dead body killed everyone else (they may have been close to the tipping point anyway). Did you notice, at any point from Sunday to Tuesday that the other fish were hanging at the bottom of the tank? This would indicate a higher-than-they're-used-to ammonia.
If your water is as jacked up as it appears to be, the amount of bio-balls you're using is not sufficient. I would recommend you switch to pond matrix and pot scrubbies in the canister, this mix is several dozen times as effective as bio balls.
Good luck, that definately sucks.
