Are fish heads beneficial to your garden , particularly tomatoes?

Yes

fish heads will attract critters unless totally composted in a enlcosed container as with all vegetables

Definitely yes, but you may have some trouble with critters digging it up. I remember when my parents had their cabin, whenever a dead fish washed up on the shore I got the chore of taking it out to the garden and burying it. Heads, guts, whatever you have would do good. Don't bury it too close to the roots, as you may disturb the roots.

It’s great for corn and beans. I’m sure the tomatoes would like it. This may be a stupid idea, but if you have a blender (less than $20 at discount store) that you can take to a porch or patio, you could chop the fishy stuff with some water. Then you could pour the stuff into holes before planting, or near the growing plants without disturbing the roots! Add some garlic, and it might repel cats and other smellers. ☺️

You betcha!

Yes... bury the fish head out from the roots and then sprinkle cayenne pepper on top of the soil to repel cats and dogs (dogs like fish too)

Things like spent coffee grounds and crushed egg shell are good for tomatoes. You would need to bury the fish heads deeps so they didn't stink, so it might be better to crush them up and compost them, but the short answer to your question they could be beneficial to the soil