It's frozen, look at Kenfish frozen section. Petsmart I don't believe has it, but check some local shop's. They might have it, but it will more expensive. The Mysis petsmart will have is def inferior & nowhere close as appetite stimulating
Day 20 update: I tried some hikari mysis shrimp last night and still no luck. My pleco and gold gourami mop up the food. i am a bit worried bcuz he getting thinner each day. I have even considered moving him back to the big tank with other dats so he can learn to eat. Problem is that the other dats are aggressive.