I found Harold's body in the filter. I am heartbroken and confused. The filter is aquael asap internal filter and came with the fish tank. It is very gentle with no suction. I just cannot understand how Harold got in there. I was treating the tank with king British white spot control. Just one hour before I found Harold he was swimming around normally. I tested the water and found 0 ammonia 0 nitrite and 10 nitrates. Does anybody have any idea what could have caused Harold to die?