The safest brand of tuna to eat is Bumble Bee Tuna, Chicken of the Sea tuna, StarKist tuna and Safe Catch tuna.
Skipjack and canned light tuna are lower in mercury levels.
The black stuff in canned tuna is just either dark muscle tissue or even bloodline meat, which is natural and a part of the fish and is very safe to eat.
The darker meat in the canned tuna has a higher concentration of blood vessels as well as myoglobin, which is an oxygen binding protein, that makes the tuna richer in flavor and a slightly different texture when compared to lighter colored tuna meat.
Some people find the taste of the dark muscle or bloodline meat in the canned tuna to be slightly bitter and prefer to remove it although it's okay to eat it.
Canned tuna is healthy for you and it's a good source of vitamins and minerals as well as omega 3 fatty acids and protein.
Tuna including canned tuna is a good source of lean protein, which is also important for building tissues and repairing of tissues and can also help you with weight management.
The omega 3s in tuna such as DHA and EPA, are also beneficial for heart health, brain function and reducing of inflammation.
Canned tuna and fresh tuna also provides you with essential vitamins and minerals, including vitamin B12, selenium, iron and vitamin D.
However due to the mercury content in canned tuna and fresh tuna you have to be careful and not eat too much of it or you could get mercury poisoning.
Skipjack tuna is often lower in mercury levels than yellowfin tuna and albacore tuna.
Canned tuna is already fully cooked and ready to eat straight from the can, although you can also heat it up or cook the canned tuna in with some other dishes like spaghetti or anything else you'd like to add the canned tuna into.
Canned tuna is already cooked during the canning and packaging process so all you have to do is eat it as it is or heat it up if you prefer to heat it up.