i would be keeping the plec and shifting other fish to make room for it. you dont actually have many bottom dwellers on the list, and now the loaches have gone the fish thats going to get biggest is the spotty plec. 7 cories is nothing, though if you found somebody to take the odd ones off you would be better for them, if not not the end of the world. clown plec will stay small, brissy plec wont get too big. and thats it. your overstocking problem is all above bottom level. and that plec is the best looking fish in the tak.