Sounds and looks alot like the coubeeyon made with gar that my Uncle Bee from Morgan City used to make. Man was that good.
Oh Lordy, that SOUNDS good!
Bet it was killer!! They're just people who flat know how to COOK...
I was travelling to Cajun country on business routinely for a few years in the mid-eighties, and consistent with the nature of southeast Louisianans, the family of one of my clients considered my visits social as much as anything. They taught me a great deal about living in general, and specifically, showed me how to cook their way.
First, I get a big pot of water boiling, then I toss the fish in. Gills and guts have been removed but that's all; heads, fins, scales, everything else goes in. Give it just a little while (~10 min) and fish 'em back out, the idea is to make boning easy. Carefully remove cooked fish meat from carcasses, no stray bones please, and toss carcasses back in. Chunk an onion in with 'em if you want. Boil for another hour, more or less. Strain. This makes a fish stock, or a 'fume' as the chefs call it (pronounced f'yoo-MAY).
The above is the most important part of making really great Cajun dishes like this, or gumbo, etouffe, etc. Always boil shrimp, crawfish, or whatever with heads on, and make a good solid stock. Or broil and reserve the juices. Or whatever, just NEVER use plain water! Canned chicken broth, clam juice, beer... anything but plain water.
Well okay, there's two most important things. Some folks don't use roux, but then, some folks are communists. (I understand some genuine organic home-grown Cajun cooks dislike roux, but I never actually met one.) It's well worth your while to learn to put a roux together, as it's a heck of a lot of fun, and one hugely versatile building block all chefs learn early on, upon which myriad dishes, sauces, and gravies are based. Roux can be made ready anywhere from almost snow white (think cream gravy) to chocolate brown (andouille gumbo).
I make the roux for thisun just as they say, a medium-light peanut butter color. Then I add the tomato paste and chopped veggies to it when it reaches that color, and cook till everything looks nicely done and juicy. Mind, it starts out looking impossibly dry when you first combine all that junk to the roux, but stay with it, it'll come around. Use medium heat, no need to go too slow or too fast. Keep stirring; if the phone rings, don't answer. Then add other spices, stock, and fish as directed.
Couple ways to address the heat issue. One way is to add Rotel tomato, another is to bump up the cayenne, yet another variation adds a minced jalepeno (or two or three). Be conservative until you know the lay of the land, this dish tends to be hot all by itself somehow. I add a sprinkle of cayenne and call it a day, and if anyone wants it hotter that's why God created Louisiana Hot Sauce.