In my goldfish tank, I have had an outbreack of annoying algae that grows on the glass. Ive tried to get it of with an algae scraper, but it won't budge. its green and splotchy. i'm thinking of using a razor but won't that damage the glass? Is there any algae eater that lives in cold water? If not, could I just slowly adjust the temperature like one degree a day? I think that would work because goldfish usually live in ponds so there used to the temperature changes. but also, I have a supposed "mosquito fish" but I really dont think she is one. I'm pretty sure shes a metallic livebearer, because mosquito fishes have a stripe, and she doesnt. but on the other hand, shes living in water about 68 or 70 degrees and mettalics need around 74-82. so im not sure. is there some kind of brown, small fish that lives in cold water?