it is just enriched brine.
Not great as a stand alone but many LFS use it since many fish that normally are hard to get to eat will take it.
LFS usually dont have the stock long enough to make much difference. Its not really a full diet for long term for a customer to use as stand alone.
spirulina is an algae so its a good additive but if thats all that its fortified with other foods are better since adult brine have no nutrients to speak of. some of the foods are enriched with vitamins and minerals along with the spirulina but IMHO I wouldnt feed just this type of foods to any fish. they all benefit from a varied diet.
Since brine shrimp is the topic. I have a question maybe some of you can answer . I keep hearing brine shrimp is not a nutritious food for fish . But I know a few breeders [freshwater and saltwater fish] that feed the baby fish brine shrimp as that is all they will eat at the time and grow really fast just on live baby brine shrimp . So if they are not nutritious why do so many breeders feed them to the baby fish and grow up to healthy adult fish ? I also know people that all they give their fish is live or frozen brine shrimp and have the fish for years . From what I have been told all these years brine shrimp to fish is like candy or junk food to us . We could not live healthy if all we ate was candy junk food . So how can the fish if it is not a nutritious food ? Something I`ve been wondering for years and figured I`d ask .
BABY brine are nutritious but they loose nutrition very fast, fresh hatched with yolk sack are what breeders feed, frozen brine is mature and nutritionally void, frozen baby brine is better. there is about a 12-24 hour window of nutrition then they are junk food.