an rtc would be way cool in your pond, tank mates are more vast than you may think... im my 400 gal tank i have an 18" rtc, 13" pacu, 18" clown knife, 7"in red devil, 7" mangunese {spelling may be off} and a soft shell turtle about the size of a cd. i plan to buy a large tsn and a pecock bass in the future... hehe i like a lot of fish that are big and stuff.