Should reduce inflammation (and thereby brain swelling which can cause damage given the constrained space inside the skull) reduce oxidative stress due to the anti-oxidant properties of the the polyunsaturated fatty acids it contains, and help in neurogenesis (rebuilding of brain cells) as the same polyunsaturated fatty acids (DHA and PHE) are pretty much the bricks that brain cells are build from.

It's also good for your cardiovascular system, and a good cardiovascular system should result in better blood flow and consequently better healing.

There's been studies done on rats which showed major improvement in (artificially) concussed rates which were given fish oil.

My neurologists has some concerns that fish oil might not have the same effects on humans given the differences in the physiology of the two species, but if you're otherwise healthy and have reasons to believe you don't have brain hemorrhage (fish oil can reduce blood clotting and function as a blood thinner), then fish oil in its recommended dosage shouldn't hurt.

If it's not helping me with my concussion, then at the very least it's totally improved my skin as side effect (My skin's been like a baby's ever since about a week after I started taking it).