It's quite possible that most of us simply don't the answer to your question, I've kept sturgeon and I now have paddlefish but I'm not convinced that either require a special food (well for paddlefish it does have to be floating food). The main thing to keep in mind is that if you are keeping a fish in cold water fish food meant for tropical fish might be hard to digest in cool or cold water. I tend toward live food when ever i can for my fish and or freshly prepared food. I also like freeze dried krill for my fish, generalist food will usually work for most fish and sturgeon in the wild are not picky eaters at all. On the other hand if a major fish food brand like Hikari (I use Hikari for my paddlefish) comes out with a food especially for a particular fish I think i'd at least try it if I could. Having said that I suspect that some of the specialty foods are more hype than science but that's just a suspicion but it is backed up by almost 50 years of successful fish keeping...
