I'm not putting the guy down, and technically all fish fry will feed on infusorians upon hatch if present. Infusoria will be present in the aquarium to a certain degree when plants are kept.
Striatum are quite large fry and they would not survive long if dependant totally on infusorians. If plants are present then naturally the fry will go for the first food available, I culture my own livefoods including Infusoria and I would never think of adding it to a tank full of Striatum fry.
That said
Microworms would be easiest but brineshrimp have more nutritional value.
After a week or so then try them with very fine (dust) sprinkle of flake food.
Regards
BigC