Buy Scuds locally on Craigslist
Buy Scuds on Amazon (paid link)
Scuds are one of the best and easiest to culture live food for fish, newts and other aquatic pets.
Actuall, scuds are the best. I keep scuds in all my aquariums.
And scuds also are great in self-sustaining self-feeding aquariums of any size!
Just Add Water Aquarium with Scuds
Feeding Gammarus to Fish
Farming Scuds for Feeding Aquarium Fish
Gammarus in Aquarium