There's Kool-aid in that water

I have a mass suicide going on in my fishtank, and it's not pretty. I woke up to find 50% of the population either floating or stuck to the filter.

There's a desperate rescue attempt for the survivors, but I'm afraid they aren't going to make it. Either the heater went out - cause the water is at 72, when it should be at 78 - or something is in the water, because it looks kinda funky.

Or they got a hold of the Kool-aid.