i have a 30 gallon tank with a 60 gallon filter and a 30 gallon heater i used to have around 250 fish and now all of my fish fit perfectly into a 5 GALLON!!!!!! What happened to all of my FISH!!!!!!!
Apparently, they died. As said above, probably from ammonia poisoning. How about looking into proper fish care, because obviously if you put 250 fish in a 30 gallon, you dont know what you are doing.