*Warning God playing golf, do not enter*
FORE!
Ontopic: I have a pet rock. Cheap to care for.
I suggest you adopt a pet rock to replace your common household pet such as fish and dogs and cats. Your pet rock can also defend you in certain circumstances. It's very safe to have multiple pet rocks, there's no fighting between the males for the females.
Although studies have shown that there really is no difference between males and females.