Baby catfish in the fry stage eat the same foods that any other egglayer fry would eat. Egglayer fry eat the smallest foods that can be given, including infusoria, which is a culture of swimming protozoa. After a week, catfish fry can also eat nutritious brine shrimp and nematodes.
Aquarium hobbyists can culture their own infusoria and nematodes at home. Infusoria is easily cultured with a jar 75% full of clean water and a few rotting lettuce leaves. No starter culture is required. Nematodes or microworms require a starter culture and a small amount of water-soaked oatmeal. With both cultures, a thriving colony of infusoria or nematodes should be evident within days.