I really want to know the answer to this as well. I also wonder about most Oscars, Iridescent Sharks and Clown Loaches since I see those fish EVERYWHERE and very few people would have a tank large enough to keep them. Fish stores always seem quick to reccomend a Pleco to clean up algae when they are not the best solution for most people. I actually had a lot of trouble finding a small Pleco when I decided to get one. I have no idea why stores stock these fish so readily when other options are availible to make people happy. When it comes down to it, fish are a product and pet stores want to make money. Only a couple of the fish stores where I live make sure people understand what they are getting into when they purchase a fish that will grow a lot. Both of these stores are non-chain pet stores.
I would like to think that these larger fish find homes with experienced fishkeepers. I think the reality is that the fish outgrow the tanks and die early, or that they get flushed. Once a fish gets to large for a tank, it is doomed to create too much bio waste for its own good or stress itself to death.
