Do fish really have loins?

Being unemployed, I consider it my duty to make dinner for my family, who is temporarily sheltering me. Since I'm horrible at home remodeling or repair, this is my way to be useful.
The other day I decided to make a fish recipe. A brief search of the freezer turned up a package labeled "Tilapia Loins." Although tilapia was perfect for the recipe, I was confused. The cartoony skipper on the package - his autograph read 'Captain High Liner' - assured me that these were the finest fish loins I could get.
Clearly I was missing some basic knowledge that would make it OK for fish to have loins, which until that day I thought were located somewhere close to an animal's inner thighs.
I was used to seeing pork tenderloin and top sirloin at the grocery store, but never saw any fish loins. In fact, I thought pork tenderloin was tender because it was a cut of meat located close to the pig's unmentionables - no doubt its tenderest parts.
An Internet search seemed to confirm my worst fears. From phrases.org.uk - "

Should you be asked to 'gird up your loins', or otherwise wonder where your loins are exactly, you could refer to this rather coy definition from the [Oxford English Dictionary: [Loins]: "The part of the body that should be covered by clothing."

That is what might have been called in the UK throughout most of the 20th century as 'the nether regions', and more recently 'the wobbly bits'."

The wobbly bits? Yuck. Captain High Liner may have been selling the best fish loins, but did I want fish loins of any quality?
Fortunately, another search somewhat clarified matters. From wikianswers.com -

The tenderloin is cut from the Psoas Major muscle that runs along the central spine of the animal be it cow, sheep or pig.

Whew. Though it doesn't mention fish exactly, this definition was decidedly more palatable.
As far as I'm concerned, the question remains. After all, isn't it redundant to give a special name to the meat surrounding a fish's backbone?
Just call it fish.