Well for fish, it's not such a big deal. Actually fish are quite beautiful and calming and can be a nice lesson in taking care of something for a child...something a little more minor than a dog.
Unfortunately, dalmations rarely fare so well. They are extremely hard to train and usually end up unwanted in a pound. This is why I always cringe when a cute dog is featured in movies or on TV (like Eddie on Frasier). Because a dog is a boatload of work and I can't stand to see the way they are tossed aside by people when they aren't as cute and fluffy as they are on TV or in a movie.
ETA: it really did (and does) happen. With rabbits at Eastertime, with any cute dog in a movie or on TV.