this is what I found from a resolved question about your exact situation, (with same bree of turtle)
"first is its tank the right temp?? cool water will put them off their food, they associate it with hibernation.
baby turtles are more carnivorous than adult turtles, shrimp, baby guppies/goldfish but not all the time (half dead, leave out of water) they provide calcium and protein, I buy dried mix of shrimp, baby fish etc. worms may need to be small.
try waving the food in front of them with long tweezers, they like it to be moving.
mine would eat shrimp all day everyday, if i let them. Look online and there are alsorts of mixes avail to feed them. a local guy here makes fresh turtle mix. look around, mine also like boiled eggyolk, meal worm.
they are like children, no owner will have the same food combo i dont think, they can be fussy."
hope this helps