CheepCheep

Cheep-Cheeps (Japanese プクプク Pukupuku) are fish that made their first appearance in Super Mario Bros., and have shown up in many other Mario games ever since.

According to Paper Mario: The Thousand Year Door, Cheep-Cheeps have their own language, which is also called "Cheep-Cheep". This language is presumably spoken natively by Cheep Cheeps, and it is only partly heard through the character Chef Shimi (who often mixes words, such as "saved" and "shaved", up due to his unique language knowledge). However, in Paper Mario, the letter Sashimie wrote to Sushie is written in Mario's language.

CheepCheep
Lined, Lineless

By Mastermind777, info from Mario Wiki