I'm pretty sure that Algaefix killed my fish. About 2 months ago my cichlid tank suffered an algae bloom. I put in the recommended dosage of Algaefix and was simply amazed at how quickly my tank cleared. I mean it was quick. The next morning however one of my Fuelleborni cichlids was acting very erratic, and actually started floating to the top. I waited just a bit before pulling him out - and literally 24 hours later he was fine.
Well I did the same thing this past Friday. I used the recommended dosage, and 24 hours later half of the cichlids in the tank were listless - breathing but clearly something was wrong (one of them, could not close his mouth). The next morning - 5 cichlids were dead!!!
I am never using this product again, and agree that it should be banned. It is completely insane that this product is on the market.