For the fish you can use catfish, carp, sea bass, etc. Remove the skin of the fish and cut into bite-sized pieces. Shell, de-vein and cut the shrimp in half.
Heat the oil in a saucepan; saute the garlic and onions 10 minutes. Stir in the water, orange rind, bay leaf, chili peppers, anise, saffron, and sherry. Bring to a boil and add the fish. Cook over medium heat for 10 minutes.
Add the shrimp and cook over low heat 10 minutes.
Mix the cornstarch with the soy sauce and a little water to make a smooth paste and stir into the soup until thickened. Add the pineapple and cook 5 minutes longer. Taste for seasoning. Discard the bay leaf.