While eating a fish sandwich, a question came to mind. Why is meat from fish so soft and flakey, while meat from mammals is tough and stringy? While they have many anatomical similarities, there are obviously some major differences in how their muscle tissue is constructed.
Perhaps a higher water content in the fish?
Or maybe the muscular strength needed to support your own weight outside the water makles it stringy?
My WAG is that fish muscles don’t need to contract as far as those of land animals so the fibers don’t need to be very long.
Fish muscle tissue is arranged in layers, which you’ve seen before. The layers are arranged for lateral motion of the fish body, which is the major source of propulsion. Most of the muscles attach to the spinal column or extensions from it. These layers are not bonded strongly to one another, and fibers within layers are all pretty much parallel. When cooked, the relatively weak structures come apart easily = tender and flakey.
Mammalian muscle tissue is arranged differently; there are discrete muscles that transmit their forces to points at (usually) bone attachments and cause the joint to move. Within one muscle there are structural elements that tie all of the microscopic contracting units together more tightly than in fish muscle…and the muscle itself is bound within connective tissue sheaths. If you picture a round steak, you can see that there can even be several muscles within a particular cut, each with its own binding system. When cooked, these structures do not come apart easily. However, if cooked slowly enough, the binding system can be seen to a larger degree…think pot roast and you know what I’m trying to illustrate.
This is just a guess based on the comparative anatomy of fish and mammals in general; there may be other differences at the micorscopic and biochemical level.
Dinner at my house can be interesting…We don’t just carve the turkey, we learn about bird anatomy!