1. Your conversations with your mom start with "So how's your fish?".
2. When people know your fish by name. (It surprises me how many people are content just to call your fish "fish" or "fishy")
3. People will NOT talk to you about fish because you either will talk about them forever, or you will argue to the death that fish have personalities. My brother is one of those people now.
4. People ask you how you can tell what your fish is feeling. (Seriously non-fishkeepers?)