What does it mean when people say I have fish lips?

"People say you have fish lips" means: Your lips look like a fish's mouth.

This sentence reminds me of my deskmate:

My deskmate is a very humorous person, very funny. He always likes to give others nicknames, and he likes to start from Make a fuss about other people's facial features.

One time, on a whim, he started chatting with the girl at the front desk after class. As they chatted, he started giving them nicknames and said something like this: "Your eyes are so beautiful, like The goldfish eyes are very big and protruding. Your mouth is also very beautiful, the shape of your mouth is like a fish lip, which opens and closes." Later, the girl was very angry and chased him everywhere and beat him, which made everyone very embarrassed.

Yes, everyone has their own way of speaking and doing things differently. Don't care what others say about you, because it only represents their opinion. So the best way is: have confidence and just be yourself.