I consider “tuna fish” to be outdated and regional to the South and maybe Midwest US. I grew up hearing it but at some point started wondering why tf we would say that rather than just tuna, so I’ve made a point to just say tuna since then.
Huh, I grew up in the South and never realized it wasn’t normal to say tuna fish sandwich. I guess it doesn’t really make sense, but I still kinda like the ring of it