I don't think that it's fair to place all of the blame on the FDA - consumers have all of the info available to them, if they choose to do a bit of homework. As an example, I knew about the dry matter vs wet matter basis of ingredients in dog & cat food over 30 yrs ago, as I chose to understand exactly what I was feeding my dogs.
But I agree, some of this can definitely be confusing to consumers, especially when one is bombarded with slick manufacturing propaganda.
Omega is a classic example, in so much as most of their "Fresh Fish from Alaska" turned out to be nothing more than plant processing waste. As far as I can tell, the only fish food still made in Alaska by Omega is their frozen food, Omega has been based in OH for several years now. Someone brought this up with Dennis Crews on his Omega forum a year or so ago, and shortly after their forum magically disappeared. It's been "under construction" ever since.
Certainly it's impossible for any consumer to ever know with 100% certainty what the inclusion rate is of each & every ingredient in any pet food, as no manufacturer in their right mind is going to list all of that information for public scrutiny. Having said that, if one knows what to look for it is possible to sort a lot of it out, and of course at the end of the day your fish will be the final testing ground. I've always suspected that Omega had a lot more starch in their food than what they would have everyone believe, and my recent experience with their marine formula certainly proved my suspicions to be true.
Every species of fish has a breaking point with regards to how much starch they can assimilate & utilize in their diet, the same thing applies to dogs. The rest just ends up as pollution in our tanks, or stored as fat by the fish. Either scenario isn't ideal for the long term health of any aquatic species.