Common pleco ? Species matter; and yea a 55 is too small for a 15 inch common pleco. There are other species of pleco that get over 15 inch so maybe it is something else but either way maybe an upgrade to 180 or 240 is in the near future ?My Pleco is about 15" long and she's in a 55 gallon tank, and laying eggs apparently, does anyone know what the breeding pattern of pleco is? We got her about a week ago, and she just laid eggs today.