Perfectly normal, in fact a stressed pleco is one that is out in the open or hanging on the glass. Plecos prefer lots of hiding places and will often dig under decorations such as driftwood to hide during the day. Once it gets dark, they become much more active.Well on Monday I bought a rubber lipped pleco and until last night all he has done is sit on the glass in one corner of the tank doing nothing. Today I noticed that he/she has dug a pit in the sand like GBR'S nest and he/she is laying in it. when I stand next to the tank for to long he goes back to the glass. Oh and the "nest" is rite next to his spot on the glass. Is this normal for s single fish of this species?