Warning: I'm not a Cichlid guy. Now read on...
I think putting the O's in the 20long will buy you a little more time to get the 110-180G you were looking at. I would skip the 75G. The Oscars will outgrow it, then you will be on the hook for yet another large tank. Plus you could fit a few Botia Kobutai in there with the Oscars...hehe
Convicts will breed like crazy, so consider the extra time & attention that will take. Plus, that 20long will be empty again in a few months after the O's move. More time to decide.
IMO If I had an extra 14g laying around, I would probably do a small brackish tank. Either a pair of Figure 8 Puffers or a Molly/Guppy/Platy/Invertebrate tank to breed my own feeders for the Oscars. Go take a look at the "End-All Mini-Monster Thread". I forget which forum its in, but just do a search. There are some great small tank fish in there.
I think putting the O's in the 20long will buy you a little more time to get the 110-180G you were looking at. I would skip the 75G. The Oscars will outgrow it, then you will be on the hook for yet another large tank. Plus you could fit a few Botia Kobutai in there with the Oscars...hehe
Convicts will breed like crazy, so consider the extra time & attention that will take. Plus, that 20long will be empty again in a few months after the O's move. More time to decide.
IMO If I had an extra 14g laying around, I would probably do a small brackish tank. Either a pair of Figure 8 Puffers or a Molly/Guppy/Platy/Invertebrate tank to breed my own feeders for the Oscars. Go take a look at the "End-All Mini-Monster Thread". I forget which forum its in, but just do a search. There are some great small tank fish in there.