Thinking more freshwater... I am moving towards Africans and I am cutting fat/too much protein from the diet..For saltwater fish I'd rank Krill and Mysis at the top, then Daphnia and Brine.
Pacifica Plankton and lobster eggs are also excellent marine foods.
With the flat rate shipping on food from them, I tend to order a year's supply at a time to get the most out of the shipping cost as I can. I also see if anyone locally wants to order any at the same time to cut their shipping costs.
I'm surprised your clownfish won't eat it. All the clownfish I have will eat any type of fish food I throw in the tank. Give it a little time, and perhaps try mixing some of the mysis shrimp in with the food you were feeding them previously. If that doesn't work, you may want to look into a food additive, such as Selcon, to help entice them into eating the mysis.