No actually its not okay to take any fwild fish from a pond and at least in colorado in utah sunfish are gamefish so if you leave in either of these places you have broke the law.
o ya I read a book on rules and guidelines on fishing and only crappie and rockbass were on the sunfish list. I did not have the correct info strangely.
I have had success housing the Green Sunfish with (MUST BE LARGER) Dovi, Butterkofi Tilapia, Jaguar Cichlid, Johanna Pe and ed Belly Pirannah. The green sunfish is extremely agressive and should be considerably smaller than these cichlids or they will kill the far less agressive cichlids. The Greens I kept with the RBP's were roughly two inches larger than them. This proved not a good fit, as the two green sunfish beat the unholy living heck out of the three RBP's. I had to remove the Greenies and return them to my farm pond as they were far to agressive to allow them to "kill" my RBP's. They did however educate the pirannah to take thawed meat as food where they never considered it before watching the greenies devoure them!
I have had great success using the green sunfish as a food source for my Longnose Gar as well as my Bowfins. The less than stellar greenie is basically what they look like homed with Bowfin!