If you mean different types there is loads (and ways to)o
Flakes - crushed or not, to give the fish a challenge or a feeder http://images.nitrosell.com/product_images/9/2087/large-live-worm-feeder.jpg
Freeze Dried live foods - just stick them in the tank or use a feeder (http://images.nitrosell.com/product_images/9/2087/large-live-worm-feeder.jpg)
Live live foods - feeder or sive them and put them in
Wafers - Algae flavoured usually, could break them or put them in whole
Frozen live foods, defrost the cube using tank water, or put the cube straight in or use a feeder http://images.nitrosell.com/product_images/9/2087/large-live-worm-feeder.jpg
KItchen Items - peas shelled crushed or not crushes, cucumber and courgette cut a slice and use a weight generally good for bottom dwellers, finely chopped spinach or any of these on a cocktail stick
Mix it up - any selection and mix of stuff!!