No need for them but some may give a good flow to the tank. We used to have albino tinfoil barbs, monos, clown loaches, and rainbow sharks in our setup. We had a hard time with the clown loaches because of the water parameters so we finally went all malawi. I'd say a good replacement for non-cichlid dithers would be some non-aggressive mbuna to keep a good flow in a hap/peacock setup. We currently have yellow labs and acei and haven't had any problems with them.