In my opinion a food item's merit has more to do with its content and not much to do with where it may be from originally.

I found the folowing data on the usda website. Based on my (admittedly limited) research I am feeding my snake a varied diet trying to cut down on the high fat items since her activity level will be lower than in the wild. But maybe some of the expert forum members can help translate the nutritional information. I'd also be interested in seeing the nutritional information on some of the other feeder fish (the usda study excluded fish for some reason).