I am going to add on other thing, plecos are territorial, I have 1 12in pleco in my 90G oscar tank. 90G and 75G are the same footprint, which means there are the same length and width. Now I have some striped rapheal catfish and some convict fry that were supposed to be food but thats anoth story, in this tank my 10in Oscar and 12in Pleco fight, I will be sitting and glance over and watch the pleco come across the tank and ram the oscar, then they fight for a while and then back to normal. I had 2 Oscars in this tank at one time, one unfortunatly died in nov., what I do know is with a Rena xp3 canister filter and an Aquaclear 110 HOB filter I still have to monitor the water conditions closely. So in my experience you have room for 1 large cichlid and 1 pleco and that is pushing it.