As it happens, I have Denison's Barbs in my S Amer cichlid tank, due to an "adoption" and having no other suitable tank for them to go into. I have 2 parrots in it also, as well as 5 pictus cats. I've never seen any negative interaction between the species. I can't say that it's a recommended grouping, but thus far, I've had no trouble.
3g betta, 29g molly, 90g Amer cichlid, 90g community, 137g African cichlid, 220g water garden, 6,500g koi pond