what size tank you have? This fish get's relatively large, over 10 in. so as for now im thinking is small right? well as it grows you will need a bigger tank, and with a bigger tank comes more expenses so if u think u can't afford such thing i suggest u return the pleco if possible. They do hel to get rid of algae growing on the glass and decor , that explains why they're mostly sucking on the glass ( that's how they eat the algae growong on the glass) . BUT if what you're looking for is a "cleaning" fish and ur tank is quite small, an OTOCINCLUS is the best choice. They only grow to about 2 or 3 inches and they are great algae eaters. Good luck!!!