A fish frame is head skeleton and tail left over for filleting.
I was thinking you could use them to make a fermented fish fertilizer for your garden.
If I had the time and energy I would do this in a heartbeat, but for now I just let my extra cockerels and roosters have their way with the carcasses. After they've had their fun my husband disposes of the remains.
I had an uncle that would always bury the fish carcasses in his garden...no treatment, he just buried them about 6 inches down and let nature take its course. With as bad as out soil is out here I should probably start doing the same.