Lets put it this way; the "aquatic specialist" came to ME, in the grooming salon, for help. I unfortunately worked there after the store manager, a friend, convinced me to open up the grooming department and assured me there would be serious money coming my way. I had a 40g tank and was just setting up the 125g when working there and yet I somehow knew way more than their aquatics specialist..who by the way never owned a fish.
Since I'm a bit of an over achiever type, when the salon was slow I spent time becoming "certified" in all the departments simply because I wanted to. The only useful thing I gained was an actual avian certification recognized by the state, which Petco actually paid for me to get. Typically only the managers took this test, but I wanted to handle the conures the way I wanted, not some silly only holding the bird on my finger deal. I've gained knowledge in every department of animals through personal experience and/or working in many types of petstores since I was 18, but not one thing I learned in the little videos and books they gave me were anything new...and some of it was quite irritating. Mind you, the videos and quizzes were the basics one may need in their department. HOWEVER, if they got the answer wrong the test would simply tell them the correct answer and ask again (same question, same answers) so there wasn't any real information retained. You could even fast forward through some of the videos, guess the answers afterward and if you got one wrong, just redo it. There was no record of redoing answers or accuracy as long as you eventually answered it right.
The most help you'll get from an employee there is them simply mimicking something they heard, but these are biased and sometimes not common sense. Some general managers have higher standards and may make their employees learn more, but this isn't Petco/Petsmart as a whole therefore there will be inconsistencies. Some fish advisers may also simply have knowledge that they found themselves. This would be equivalent to talking to a stranger whose buying things in a fish store and asking them to advice. Maybe you'll get some help, but this isn't formal education and likely an opinion.