My word, Oddball, I don't know how you have the strength to not prune out all the ...less informative posts.
Have you read any of Neale Monks' writings on the thiamine issue with coldwater freshwater fish? I know that in other postings that he's made elsewhere, he cites various scientific articles on the vitamin content of these fish. Sadly, the site that I know this article is posted on is down today, so I can't find the citations directly.
In short form, Dr. Monks writes that coldwater FW fish such as goldfish and rosy reds are not suitable as feeders for freshwater fish either. As alluded to by certain other posters, this is because these coldwater fish contain Thiaminase, an enzyme which breaks down vitamin B (Thiamine). Since this vitamin helps the body absorb energy and also plays important roles in the nervous system, the excess of Thiaminase which occurs from a goldfish-rich diet directly offsets all the benefits attributable to using live feeder fish. Consideration should also be given to the fact that coldwater fish such as goldies and rosie-reds have much higher fat content than would normally be encountered by a tropical predator. For this reason, it is advisable to feed tropical predators tropical feeders such as livebearers or cichlids.
"But aren't coldwater fish used to make commercial prepared diets?" Sure, but Thiaminase is broken down by cooking (heat) and excess fat content is removed from tropical feeds. The prepared diets are then fortified with various nutrients to be appropriate for a specific purpose and designed such that most of those nutrients are in turn consumed by the fish. The trick in this case is to select a food well-suited to the fish in question--and a manufacturer who can be relied on for good quality.
I have a request! (Assuming that Oddball is even still paying attention to posts in this thread.) Would it be possible for you to post up some nutritional facts regarding tillapia as well? It seems that it could be a reasonable nutritional analogue to the tropical feeders seeing as it is (a) native to warm waters, (b) adaptable to brackish conditions like mollies/guppies and (c) a cichlid.