The symbolism of the multiplication of loaves and fish has to do with the teaching of Jesus. Jesus breaks down the Law (five loaves, the pentateuch), and the prophets (the two fish, major and minor prophets) so that all may be nourished by this teaching. The insufficiency of the Law and the Prophets is made abundantly nourishing through the grace of Christ. This was the same reality that the children of Israel struggled with in the desert. The food that God provided, the manna, seemed truly insufficient. The people wanted flesh to eat, to satisfy their cravings. God comes in the flesh of Jesus to fully satisfy our cravings. The Law and the Prophets could not satisfy the craving for communion with God because it only served to reinforce the weight of sin and separation. Jesus is not bringing a teaching that is different in content from the Law and the Prophets. Rather, He makes that teaching abundantly satisfying by fulfilling it in His flesh and multiplying it for us.