Welcome! Tuna is ok but typically canned tune, even in water, has an extremely high sodiium content and can contain high amounts of mercury so I would recommend it in small amounts. A small amount of tuna that has been thoroughly rinsed with clear water to remove as much sodium as possible is ok as an occasional treat.
You'll notice that some dog foods contain small amounts of tuna as well as salmon - Fromm has one which is a good brand to use.
You'll notice that some dog foods contain small amounts of tuna as well as salmon - Fromm has one which is a good brand to use.