I doubt much benefit using frozen cleaned fish. It's the oil in fish that is a natural fertilizer aften referred to as "fish emulsion". Better to use some quality fish emulsion with some kelp IMO. Don't want cats or wild varmits digging in your tomato bed...:)

Fish is a very good fertilizer. The bone provides phosphorous. The meat has a lot of protein which means nitrogen rich.

The drawback will be (1) cost which is not an issue for you, but wasteful if one has to buy it. (2) smell, may smell bad if not covered right and attract animals. (3) uncertainty about how long it takes to decompose, the bone probably won't do much in a season. (4) salt, if it comes from sea.

I've buried freshwater fish in my garden before and had great results. I wouldn't plant it directly under the tomato plants though since it hasn't decomposed at all. It would be best to bury it and plant a few months later, I think.
Maybe plant it deep to avoid critters, a foot or so away from the roots.

I've also buried produce scraps from the grocery store and had good results.

Pete