It's also worth mentioning that these are not perfect community fish. They have been reliably reported to be parasites on a variety of large, slow-moving fish. These have certainly included angelfish and discus, and I'd imagine gouramis too. I had to separate a trio of Otocinclus from my candy stripe goby, Awaous flavus because of this. The catfish were scraping at the skin, feeding on mucous and the blood seeping out of the wounds. This isn't supposition: I saw them doing it.
I'd suspect that these fish are perfectly safe with small, fast-moving fish, such as tetras. They are known to coexist with small puffers, too.
Cheers,
Neale
I realize that this is an extremely OLD thread, and probably this won't be answered, but will livebearers, cories and danios also work well with otos? I guess they are all small and fairly active, but based on the statements I am quoting, I am just confirming. Otos would be an addition to my tank basically to combat brown algae, which notoriously shows up in newer tanks, which is what I will have when I finally get around to setting it up. I figure having these little guys around could help keep it at bay (or maybe not even be noticeable).