so, currently i have (all non agressive) a red oscar (3"), tiger oscar (4.5"), albino oscar(1.5") and a RTC (4.5") in a 30gal who were all very happy and energetic. i had to move a pleco (5.5") from my 55gal (he was chewing on my TSN) to the 30gal. now my oscars are quiet, laying sideways, and hiding everytime we walk up to the tank. are they upset (and can they be?) about the new friend? the pleco is off in his own world and i havnt seen him near the oscars.