Well, I dont know about others...
But making money is the object, generally, 90% of working hours are taken up with a ridiculously long list of things to clean, algae to scrub, glass to spray and wipe to remove kid nose prints and snot marks, gravel to clean, weirs and pipe work to clean, light trays to keep clean, floors to hoover, water changes to be done, dosing tanks and systems to be done, maintaining display tanks to be done, treating fish, moving fish, labling up fish, replacing lables when halfwits keep stealing them, acclimatising new fish and changing over lables, death checks every 15-30 minutes, pond plants to look after by trimming, changing water, moving about... then you have stock rotation, new deliveries and pricing up and checking off invoices, planning new orders with all the codes and item names painstakingly found found from the long item lists. Oh yeah... aquarium plant tanks need regular water changing and plants need rebunching and moving around and algae wipe those tanks too.
Pretty sure that covers a day or twos list of jobs....
THEN there is the customers.... (of course, the above jobs are done with interruptions every 5 minutes because customers walk right past staff waiting at the till and ask the person cleaning tanks to catch fish because they are either too stupid or too lazy to walk the 20ft back to the till).
You do NOT turn customers away with the exception of them blatently not having suitable tanks according to the companies standards. So most would say... all tanks must be filtered...
p@h for example insist the tank must be 'cycled' for 3 days, other companies dont have a length of time set in stone as it doesnt work like that. And you obviously wouldnt sell marines to a freshwater tank or vice versa etc. Other than that... its pretty much up to the member of staff's discression, though bearing in mind that if they want to keep their job, they wouldnt want to be turning away customers and losing sales. This is also a case whether or not the said member of staff has any experience or training.
Few companies provide training and those that provide basic training cant provide experience or in depth training. I mean... when you stock hundreds of speies of fish, how can you quickly train a member of staff in all of their details and requirements?
That said, the staff have to be motivated to learn and they can only do so by experience, member of staff has to be SERIOUSLY motivated to go out and learn all of this information for themselves and work for very basic retail wages. It is a hobby and a job, not a career that is fulfilling and you can support yourself financially on. But some days... there is a customer (seriously.. like 1 or 2 a week if you are lucky and they are usually the regulars!) that make you think thank god somebody out there appreciates the work done by the average lowly 'slob' working in your LFS because honestly, fishkeepers can be the most apalling people to work with.
Interrupting the work being done to spend hours telling member of staff how it ought to be done, how they would do it, how people on the internet say it should be done. Where they can buy it cheaper on the internet (like its our problem? You can find it cheaper on the internet... go buy it cheaper on the internet! or ask if shop does price matching or just shut up and put up and take into account that the extra money pretty much covers the time you have just wasted in whining at the member of staff).
Fish keepers all want something for nothing, far more than any other hobby involving animals I have worked with. Exclaiming "how can such a small fish POSSIBLY be worth £2!?" (bearing in mind said fish could live as long as some of the large breeds of dog and how much do you pay for one of those!?).
Fish keepers also vandalise things as much as anyone else, by allowing thir children to run riot, smacking tanks, pointing at fish that are already clearly stressed out without people waving hands in front of tank, moving stock from shelf to shelf, knocking things over without picking them up, breaking things, stealing fish lables and stock and I dare say even fish too.
I will never understand why fish keepers always seem to think they know best and have a real attitude with no real consideration to all the other factors, its always they customers that start with "well on the forums they said..." or "I read on the internet" and straight away you want to just shove them in a pond and run away just to make them stop with those comments.
And your worried about a couple of silver sharks? Unfortunately the aquatics industry is NOTHING like the rest of the pet industry and whether you like it or not.. that is a fact. If you had to do 15-30 minute death checks in a pet shop with fluffy animals, you'd have long since been closed down and yet this is a norm for working in aquatics. Its pretty soul destroying to be honest!
But generally silver shark conversations go:
Customer: Can I have 3 of these please?
Staff: Certainly, but you do realise how big they get dont you?
Customer: Yes, I have kept them before and they lived for years!! They died recently of old age!!
Then you have to think at this point, is it worth contradicting them and pointing out they couldnt possibly have died of old age when they were only 3 years old and about 4" long? Because you would effectively be saying to them "you are an idiot and managed to kill your fish through neglect". Ironically... it is usually the exact case and would be wonderfully theraputic to actually be able to say!! But generally... it would be deemed inapropriate. You dont point out to customers they just murdered their pet.
Staff: You do realise they ought to be growing to about a foot long and need a much larger tank to live in?
Customer: Yes yes, we'll get a bigger tank for them when they get big, we were planning to get a bigger tank anyway... so can we have 3 of the sharks please?
By which point... short of flat out refusing to sell the fish and risking losing your job because selling those fish breaks no laws and doesnt break the companies stated rules... what can you do but sell the fish?
my post was aimed more at those "so what does the member of staff actually do?" comments and I maybe have given in to the rant a bit 
