This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Fish may be cooked by boiling, grilling, baking, frying, or stewing. Of these several methods, boiling is decidedly the most advantageous for persons with feeble digestions, and next in order is broiling. When fish is boiled without the addition of salt to the water it becomes soft and disintegrated, but if boiled in sea water or artificially salted water it maintains its shape and flavour. The quantity of salt present regulates the osmosis of the juices of the fish into the water. As a rule, fish requires much less time than meat for cooking.
If fried fish is to be eaten by dyspeptics, it should be cooked whole, and the skin must be carefully removed subsequently. It is never as digestible as boiled fish.