Top positive review
They are all gathered at the top of the tank looking like they can't breathe...please see comments for the fix.
on August 18, 2017
I've used many other Tetra products and never had issues, so not sure how to rate this but trying to be fair. The manufacturer says it is not harmful to the fish but the day after using it during a water change I had 1 Chinese algie eater die and the other fish haven't eaten since. They are all gathered at the top of the tank looking like they can't breathe. All of the fish in that tank are large, the one mentioned and three 8 inch Oscars. I used it in 2 other tanks with much smaller fish and they seem OK. This tanks is however the only one with some sunlight and has a large piece of drift wood in it with a little white algie growing on it. It seems to also be leaving a film on the glass that the other tanks don't have. I'm not sure if the combination is creating a toxic environment or not, and its hard to kill an Oscar, but something ain't right.