Fish and dogs can be both lazy and energetic depending on their mood. However, the fish are confined within the four glass walls of their tanks. Since the fish are unable to leave the tank, this poses no liability to the owner in having to deal with a hyperactive fish. This is also convenient for those who don't have much time to spend with their pet. Unlike a fish owner, a dog owner should take him for a walk to release some energy and keep him fit. This is a much bigger responsibility for dog owners because the built-up energy can become destructive if not dealt with properly. When deciding to purchase one of the pets, a main point to consider is whether the owners have enough time to spend with a dog, or whether they have an extremely busy schedule and need a fish that is almost self-contained.