I have been doing a little research on fish/creatures to control algae in aquariums and have had no success finding something that is compatible with rays. I have a small Retic and my tank is having a bit of an algae problem. It is not severe like green water or anything, but it forms on some of my decorations and tries to form on my glass. I do water changer twice a week and my water quality is good, but my apartment is bright with sunlight. I have read that there is a risk of plecos and flag fish sucking the slime coat off of the ray, and the ray will eat snails, shrimp, or any other invertebrate that would help with the problem. Does anyone have any suggestions or do I have to keep scraping it? Also, is anybody keeping a pleco with their ray? I was wondering if it is an extremely rare case type of thing.