You can feed your dog any kind of fish -seafoods included.
It should be frozen for at least 10 days ( hard freeze), to kill any flukes or other parasites.
Anyfish is good. You can easily deviate away from the fatty fish if you want to because the reason we feed those is for the Omega 3+6, but they are very fatty, so other types of fish a more than positive because they offer quality protein without the excess fat, so the portions would be different
Dogs only need a small amount of fatty fish, whereas they can eat copius amounts of non fatty. ( white fish, flounder, sole, cod, etc)
Please be aware that freezing will not kill the unwanted parasite in steelheads, but the parasite is only located in their heads not in the body.
It's just best to avoid that particular fish altogether.
The best place to start to learn about choosing fish is at Oceans Alive:
http://www.edf.org/page.cfm?tagID=1521
You can learn what fish to avoid, which ones are safe, which ones you should avoid for ethical reasons.
Cheers
MM