Live foods work best. Vinegar eels, microworm, baby brine shrimp, etc. The movement they make is attractive to fry, especially labyrinth fish.
You can order brine shrimp eggs on Amazon, or perhaps other live food cultures if lucky.
Personally, I go with baby brine shrimp. You can choose to use aquarium salt or baking soda to hatch them. Just gotta rinse well with tap water, then dechlorinate when you feed the babies.
What you need:
2 containers (1 liter for one, the other can be a simple cup or glass)
1 air pump + airline (airstone optional)
aquarium salt or baking soda
Brine shrimp eggs
coffee filter or brine shrimp net/strainer
pipette or clean airline hose used as siphon
1) to hatch brine shrimp, 1 liter of water and 2 tablespoons of aquarium salt OR baking soda. Ive tried both, they work just as well. Never hurts to dechlorinate the hatching water.
2) use an airline/airstone in the container, best hatch rate at 75-82F but ive hatched in cooler temps too. Just takes longer. For 20-36 hours aerate the container. They will hatch in that time.
3) let the container sit in a cool, dark place (I store mine in the fridge) for at least 10 minutes, then use a small airline hose or a pipette to siphon out a small portion of baby brine shrimp from the bottom of the container (egg shells float, you can scoop these out) into a coffee filter (or brine shrimp net) over another jar or cup. Only siphon out what you will need per feeding, store the unused shrimp in the fridge in the original hatching solution. They will last for 3 days in the fridge. So hatch enough to last 3 days, you will figure it out after a bit how much you will need.
4) as the water drains and the shrimp are collected in the coffee filter, rinse with room temp tap water thoroughly. Let drain.
5) in new container, place fresh dechlorinated water (do not add salt or baking soda to this) and add the rinsed baby brine shrimp.
Use a pipette to spot feed the babies what they will eat in short amount of time. Any leftover can be placed in the fridge and used as needed throughout the day again.
Honestly it SOUNDS like a lot of work but other than hatching time, it takes less than 10 minutes to collect, rinse, and feed. Ive had so many babies since April, every 2 days hatching new brine shrimp. Its become routine and its not as bad as it really sounds.