While what you say is in fact very valid, It does make the differnce in the staff. But what wal-mart fails to do, is screen the staff they hire. So in most cases they have an employee that is simply there to fill a spot. But yes, on occasion they get an employee that actually knows a little or quite a bit about the subject.
Which is understandable on Wal-Mart part not to screen for pet knowledge, do you honestly think that wal-mart makes any significant money on fish sales??? not, likely.
But as far as hiring goes, when you get into a specialized position. As in a Local Fish Store, they aren't going to hire anyone that only knows how to play golf. So in that case teh quality is going to be better. Or in the larger cases, Pet Smart Etc. They will actually train (or attempt) the employees to properly look after the fish. It then falls on the shoulders of the employee to maintain the livestock. But when you talking about Wal-mart, they might spend... a Day in training, and that is to simply tell them to (try) clean out dead fish, and get rid of green slime etc. And 1/2 the time the poeple working in the pet section are only covering, and belong to other departments
LOL... what a long post... So in conclusion, i don't think that it is unfair to rate Wal-Mart on the quality as Poor, it is a corperate decision to lack in those divisions, or poor management procedures. (yes, they do get lucky and find a good employee) but on the whole wal-mart is sub par.

Flame away everyone! Just thought this might be a good counter insight