I have become slightly concerned about my little oto lately... I have a single oto in a 5 gallon tank on my desk at work along with a betta, a cory, and an ADF. The oto has been in the tank for about 3-4 months but lately it has been spending a lot of time just hanging out on the bottom. There is plenty of algae for it to munch on (multiple types) but it doesn't seem to be doing nearly as much eating as it did when I first put it in the tank. I had a lot of brown algae when he/she first went in there and he made short work of it, cleaning all the leaves on my sword plants and the sides of the tank. Now brown algae on my plants (at least I think it's brown algae), along with some bright green soft algae (NOT hair algae). I do weekly water changes and test the water, ammonia and nitrites are always 0, not sure what nitrates are (need to bring my test kit from home). Water here is alkaline and hard (pH about 8.2, KH 150ppm, GH 180ppm). I get the algae because the tank gets too much light so the sides get scrubbed down weekly but I always make sure to leave some algae in there for Oto... I will occasionally see him 'working' on the gravel and plants but not nearly as much as I used to see him moving about. He doesn't look thin, his color is normal, swimming normally (when it does swim), breathing normally, tail and fins are a bit clamped when it is resting on the bottom but not while swimming... should I be worried? Is he just bored or lonely? Someone previously suggested to me that I should put in a couple more since they prefer to be in groups. I DO plan to do this soon but the last time I saw them at LFS, there was a sick glass fish in the tank with them so I passed.