Wow - it still amazes me how stupid some LFS owners can be.
IMO -The Lemon sharks has to be the absolute worst and most ill-suited shark available to private Aquarists. For the following reasons.
1.) they get Huge - at least 9-10', and weight 300-400lbs. Also very active & require lots of swimming room - at least 50,000 gallons (at least 1,000-1,200 sq ft) for an average sized adult. and very large food bill to maintain an adult.
2.) They are very aggressive, and potential dangerous to the keeper - rated number 10, on the International Shark Attack Files with over 2 dozen unprevoked attacks on humans.
3.) This is a species in which maybe 1 out of every 100,000 private aquarists, might have the room, resources & experience to be handle this shark. For most shark aquarists - buying a Lemon is similar to a cat fancier going out an buying a "pet' Lion or Tiger.
Truth I hate the idea of seeing any unsuitable species of shark on display in LFS - Bonnetheads, Nurse sharks, Whitetip reefs, Blacktip reefs, or Lemons. Because it tend to give their customers the wrong idea - that it perfectly acceptable to keep these species. And that they in relatively small tanks (from about 500 gallons to a few thousand gallons).
All of these sharks - if kept by a private aquarist(which is debateable), require tanks/ponds of 10's of thousands of gallons.