What is the best thing i can feed them?
a mix of diffrent foods or just regular things?

Gf need a variety of foods. A good protein food such as Progold, just make sure it sinks and doesn't float. Some members use flakes but make sure to soak these as they dont' sink well.

Veggies like lettuce, squash, cukes and peas are good too.
Spurilna is also a good veggie nutrient.

GF also like oranges for a treat once in a while.

Some other stuff like bloodworms, shrimp are good as well.