Micro-pellets are great, and tiny frozen plankton or brine shrimp nauplii will make good alternatives. (petbusiness.com)
If you are looking to raise brine shrimp as a food source for your fish it is easier and less expensive to buy live or frozen adult brine shrimp from your local fish store as you can not raise enough shrimp in a small aquarium to make the effort worthwhile, but if you want to do it as an experiment or learning experience, you can start with a tank of 10 gallons or larger and limit the amount of shrimp nauplii you use as a starter. (sfbb.com)
Barnacle larvae progress through multiple planktonic stages, termed «nauplii» and «cyprids,» before settling to the bottom. (sciencedaily.com)