I think the movies intention was to discourage kids from keeping fish in aquariums. Obviously they failed. I still give them kudos for trying. They didn't directly tell people to keep fish in aquariums, they actually did the opposite.
That doesn't change the fact that they did some damage.
A few months ago I was reading an article that explained how clownfish were becoming extinct due to our hobby. Even though it is wrong/exaggerated, it still helped to show people the damage.