This bothers me a lot too. When I worked at petsmart I had to field this all the time. "I want 10 of those oscars for my ten gallon aquarium." was a common occurrence. Same as african cichlids and fantails. People get mad when they find out they can't do what they want. They even say they will get a bigger tank later on, like a 29. I also think that fish stores need to be more ethical in what they sell. Almost no one has a tank big enough to properly house a rtc, for instance. Or even worse, alligator gar or airipaima.