Fish is one of the healthiest foods on the planet. However you need to be aware that most fish nowadays contain lots of toxins and heavy metals due to polluted sea, lakes and rivers.
The safest way is wild caught fish.
Also Aqua culture is more and more common and if you are not sure where the fish comes from you should definitely buy it from there. Just make sure how the fish has been fed. Meanwhile farms feed the fish with corn and grains which are most likely GMO.
Nevertheless fish has lots of awesome health benefits. Just to mention a few: it is loaded with important nutrients, such as protein and vitamin D, it is high on omega 3 fatty acids and is rich on vitamins and minerals.
The pic shoes Lubina which we stuffed with lemon and sage. Just drizzle olive oil on top, spice it with sea salt and pepper and bake it in the oven for about 20 min.