I fully understand they do not get paid well. However, the owner/manager should pay them to at least spend a couple hours a week to research, or learn it themselves to instruct the employees. Sure, this would cost them more money, but it would make up for it with higher survival rates, healthier fish leading to more sales, less mislabelling and the ability to actually answers questions customers ask sometimes.
Fair enough, but the problem is most of these shops are barely scraping by as it is (at least over here), so for them to pay even more on top of that as incentive is very rarely going to happen if ever since we live in a far from perfect world...
Also, how can you guarantee they will learn it? by testing them each week, or even each month? i think a lot of people would turn around and just look for another low paying job that didn't require them to learn about the things they were selling... its kinda like if i were to all of a sudden lose my job, i wouldn't go and try and be a mechanic, coz A) I don't want to learn an encyclopedia worth of of new things since i already have my skill set and B) there are other low pay jobs i could probably do and still get paid the same and not need to learn a whole new load of new information and C) Who's to say even the shop owner has the correct info in the first place for all the fish?
Either way, i'm not saying its not a good idea, but sadly we don't live in a perfect world and as such, things like this very rarely happen unfortunately... although maybe in the US / Canada its slightly different? i don't know?