Death by algae??

[Borderjumper]

This hobby can be so frustrating! last night I cleaned the glass in my tank. Nothing out of the ordinary, just ran the mag float around the front. The only thing different is I also did one side, which did have a slight bit of cyano on it.

Walked back into the room about 10 minutes later to admire my handy work.. and bamm 2 dead firefish and 2 dead chromis with the other chromis flopping.
The little yellow tang and fat bastard six line are out swimming as usual.. WTF!

[Aquattro]

I know cyano is a bit toxic, but I have some spots in my tank that I regularly baste off the rocks, allowing it to float around for mechanical removal. I've never seen anything try to eat it, and certainly no dead fish from removing it.

[Borderjumper]

Yeah weirdness.. I have cyano in the big tank and regularly stir it up and let if float with no issues.. One of those things I guess.. You would think whatever it waswould have killed all the fish if it were so damn toxic.. No clue.. The mag float is always kept out of the tank in the same place and I'm pretty sure had no contaminants, and I'm pretty good about washing may hands before I touch my tanks, so it has to be what ever was growing on the glass.