I just read your comment on the Oto Catfish in the fish profiles section of the forums. I don't think the 5 fish you purchased were in fact otos. I believe you were given Chinese Algae Eaters. CAE look nearly identical (similar coloration but slightly different pattern) to an oto but are increasingly aggressive as they get older. CAEs also usually stop eating algae.

I had a CAE in with my danios. only 3 survived and two of the survivors are severely handicapped (one is missing an eye the other has a damaged gill).

I thought you should be aware of your potential misguidance.