Homemade food

[wetpets9]

I have found several recipes for homemade fish food and seen several people mention feeding live clams etc. My question is where do you get the food at? I know the grocery store has sea food but ive read it has perservatives etc in it so would that be safe to use. Have no idea where to even look for live clams. Cansomeone lead me in the right direction to get the fresh sea food.