Also, just as a general care and maintenance sort of thing, in an unfiltered smaller tank(I assume yours is under 5 gallons), you should be doing at the very least two water changes per week, 1 50% and 1 100%(though I personally find, based on my own experience, that an extra 50-ish% is good as well)to maintain proper water quality and help make sure that his biting does not end up turning into fin