Tuna can be marinated if you so choose and many people do because it enhances the overall taste of the fish. There are many different things you can marinate it in and a number of different marinating methods to use. Make sure to look through some of your options before selecting anything in particular to marinate your tuna steak in.
Lots of people marinate their tuna steaks because it adds a little extra something to the taste. There are going to be a lot of options to look at so you will want to go online and review some of the recipes that are posted by people who have tried different things.