Ok, so this isn't a fish of mine so I can't give any specific info, but a customer came into the store tonight and said that after changing to a different fish food (generic fish flake, I think it was Tetra?) the water in his goldfish tank turned red and if the fish was not right by the glass you couldn't see it through the red water. Um, he said he had 2 fan-tail goldfish in a 10G, which was overcrowded (by a lot) but still, red water?
Any ideas?
Any ideas?