help! emergency!

[surfanswim]

ahhhhhhhhhhhhhhh, all my fish are dying, i just did a 25 percent water change in my 55 gal tank, just my regular maintence. i have 2 kribs, 12 tetras, 2 guppies, and 6 rams, and a bunch of otos. 1 krib is dead, the guppies are dead and swordtails. the paramters are nnormal-7.2ph, 0 nitrates, 0 nitrites, 0 ammonia, what the hell happened? all help is appreciated, i dunt want my tank to b desroyed, thanks

 

[aspen]

something is toxic in your tank. pour out some new water in a bucket, de-chlor it and transfer the fish immediately. add an airstone. worry about the fine details later. if you don't trust your water supply, get some water from somewhere else.

rick