Since you have the whole fish here is something to do with the bits that normally get thrown away:
Fish fummet from scraps:
Save the bones, head, fins and skin. Save vegetable peels and ends form carrots, onion, celery, mushrooms, leeks, shallots, parsley, etc. Sweat veg till hot and steamy, add the fish parts, bring all to temp and add white wine, water, some lemon juice. Simmer for about 20 minutes or until it smells good, let cool a bit and pass through a linen.
An actual recipe does not matter because any way the fummet is made it will taste good, and the idea is to use up what would normally be trash. just that the wine should be about 10% of the water, and the water should less than cover all the scraps in the pot.
A fish fummet has many uses, but easiest is for a soup base, or thicken and garnish it for a sauce. It will freeze and keep alright, but better so serve it as a sauce or soup with the veg and fish you are preparing as the meal.
I suggest not refreezing fish flesh if you can avoid it because the quality will deteriorate. Normally it is not recognized as good to refreeze anything.