I would try a really good feed like LRS Fish Frenzy which has black works, roe, etc etc and should be very appealing to your fish. Some refer to it as fish crack! It is high in protein, nutrients etc.
If they will only eat pellets I would do a well rounded pellet diet. Golden Pearls makes a good pellet feed, kens fish store has a good home made pellet, new life spectrum has great food, and APBreed TDO. Mixing it up offers a good opportunity of different a nutrients and making your clowns look stunning and happy!