tin foils get too big for dither. dithers distract the aggressive fish. the ACs will chase the dithers instead of each other. go with some giant danios. you dont have to have them, it depends of how YOUR ac behave. we have a 55 with 10 malawis in it and dont use dither. i use mollies and platied in my 150 tang tank
like toehead said--giant danios are great because they can handle malawi aggression.. i have 3 malawi mbuna tanks (a 180, 90 and 47 gallon) but i chose not to use any dither/target fish with mine and they all do fine...