You can make fish sticks or baja style fish tacos. If your friend cant have wheat you can use rice floor. Rice is generally procesed in a way to remove the poisonus bits of the grain. Also cod is better smoked and fried with onion and pepper than baked.

If you must cook or fry large fish fillets, large fish like marlin or tuna or etc. have bits that look a diferent color because they have a lot of fat. these are the easiests parts to cook. They shouldnt be more expensive because people usually do not want them because of the wierd color.