Did I do it wrong? Went by the recipes, but this was tasteless crap.
Did you salt the fish?
No, because I didn’t have unsalted butter.
So you didn’t follow the recipe.
Almost every time you end up with tasteless food it’s because you didn’t use enough salt.
Hard to tell without knowing which recipe you used.
Quit poaching, get a license. 
Poaching fish in butter or oil is a good technique for certain types of fish, generally for lean whitefish like bass; this would work for most any fish except the oily ones like mackerel.
And it’s pretty easy – salt fish, melt butter, poach gently, serve. Even though the fish is swimming in butter or oil it’s not like you’re EATING a pound of butter, very little is actually absorbed into the fish, so you fat phobic types can calm down.
You can also add herbs to the butter. And use the butter afterwards to make a sauce.
Done properly the fish will have a lush texture and a light taste.
If you’re accustomed to poaching in water or stock or wine the taste will be more subtle.
Wouldn’t use fancy butter for this, just plain ol supermarket stuff. (Actually I would probably use olive oil and butter but I like that.) I would especially stay clear of the European style cultured butters, they bring other flavors that might not go so well with fish. And you need a little acid in there too for balance, lemon or vinegar or capers or something like that.
I’ve talked all around it, so tell us what you did exactly!
No, the OP wasn’t the poacher–the OP was cooking the butter poaching fish, which has a similar habit to the much more famous honey badger. When this fish (a type of mudskipper) sees someone dressed like a traditional milk maid, it flips out of the water and follows her until it finds her store of butter. As you can imagine, this fish is quite rare and the OP should be ashamed.
You still salt the fish upon serving (unless you’re trying to avoid salt; then I would still try to adjust seasoning to taste in some matter that is appropriate to your diet.) I tend to agree with Renee that many times when people complain about the blandness of the recipe, they didn’t salt it properly. No, you don’t need a ton of salt to make a dish palatable, and everyone has different salt preferences and tolerances, yaddayaddayadda, but I’ve found out very often the difference between “bland” and “tasty” is just a bit of salt.
Shouldn’t that be “tasteless carp?”
90% of everything is carp, said a famous sturgeon. 
I always add some type of herb to the butter or oil when poaching. For fish, I would usually go with dill, and maybe some lemon zest.
Some recipes are complete in and of themselves, others are a starter for the basics of a dish/technique, and you are meant to add the flavor profile you prefer.
As some were saying the type of fish makes a difference. I personally don’t like poached fish. Maybe it’s just not to your liking.
But, yea salt is imperative.
A fish trick and a fish poaching trick that might help.
For the fish, generously coat in equal amounts of salt and sugar, and let sit refrigerated for 15 minutes. Rinse well in ice water and pat dry before cooking. This works for (nearly?) all types of fish. Just be sure to remove all the external salt and sugar.
For poaching, because the top cooks slower than the bottom, start by par-cooking the top over low heat in a little butter for 3-4 minutes. Place to side, prepare poaching liquid, then place fish in poaching liquid cooked side up. Proceed as directed.
Well, not having the unsalted butter on hand, and using the regular stuff-I didn’t think to salt. The recipe recommended that if the fish were thin, I could pop in the preheated oven for maybe 5 min. at the end rather than trying to turn it. And the damn fish was thinner than it looked in the package. The recipe was from Google, natch, first page with sautéed veggies. I did use a dab of olive oil to keep the butter under control.
Ah , chalk it up to my watching way too many cooking shows and getting too many “I should try that!” moments
I use salted butter for everything, despite all the pointyheaded chefs who tell me not to, and I use the amount of salt a recipe calls for anyway (if there’s a range in the recipe I’ll use the lower end of the range), and everything comes out just fine.
If I did the math right a pound of butter has between 1 and 2 teaspoons of salt. So depending on how much of the butter you actually eat, the salt in it doesn’t matter much. Which isn’t surprising, since eating just the salted butter isn’t a particularly salty experience.
and dont use butter, use dynamite. 