Tallywell.

Mackerel (cooked) vs Salmon (cooked)

Mackerel (cooked)Salmon (cooked)
Protein · per 100 g18.6 g22.1 g
Fiber · per 100 g0.0 g0.0 g
Energy · per 100 g205 kcal206 kcal
Protein · per 100 kcal9.1 g10.7 g
To hit 30 g protein161 g · 331 kcal136 g · 280 kcal

Bold marks the better side of each row. "Per 100 kcal" answers the density question — which food delivers more protein for the energy it costs. Portion row is computed live from the same USDA base values shown on each food page.