Instruct: Classify the given Amazon review as either positive or negative.
Query: Do not use this product!

I have to strongly advise against using this product whatsoever. I made the mistake of testing this in my larger aquarium, and it killed one of my giant danios and caused immediate behavioral problems with the two cichlids in the same tank. (swimming erratically, slamming into the glass walls, etc) All of these had been in the tank for 6-24 months with no prior problems. I wound up having to do a 50% water change over two days to get the tank back to normal conditions. The bottle itself immediately went in the trash. If Amazon would let me rate this product with zero stars, I would!