I have 2 Guppies in my 30l BiOrb. recently they have started nibbling at my volcano ornament which has plastic plants on it. Would it be that I am underfeeding them? Stress? or is it just what they do?
they are probably grazing on algae. Guppies like a bit of plant matter in their diet and if you don't have any live plants then they will look for algae instead.
