Hi Kiely. The Pumkinseed are compatible with Oscars, as long as you provide a propper set up. In the long run, the Convicts will be in jeopardy of becoming lunch.
Check this link for Oscars tankmates:
http://www.oscarfishlover.com/index....tankmates.html
However. temporarely, if your Oscar is young, you could keep them together for some time, maybe even a year as your Oscar grows up.
I have two young Tiguer Oscars, one is allready 8" and the other one is 6" in a 145gal tank, among other tankmates I keep four young Convicts and so far no problems at all, but the Convicts will be housed in another tank (since they multiply as rabbits, I plan to breed them to feed the Oscars and Severums with their fry).
Pepe
Santo Domingo