Cheep Cheeps Are Pufferfish
So a little detail I found out from the description for the Cheep Cheep in Super Princess Peach's Glossary.
"A Blowfish-like creature that lives in the water."
I'd note the Super Princess Peach Glossary uses the word like for say Piranha Plants are plant like when every other piece of info from other games says they are plants.
So the like part could be a mistake or localization error, or someone accidentally adding like.
Why do I say this for Cheep Cheeps?
Well….....
The blowfish details seems to be a thing Nintendo has always intended for the Cheep Cheeps.
One example is in Super Mario Bros.: The Great Mission to Rescue Princess Peach, when a Cheep Cheep shows up and puffs itself up like a blowfish.
While the OVA is not canon the information here was probably added in based on Nintendo's intentions for aspects of the games like Piranha Plants being flowers.
Because it does match up perfectly with the piece of information from the games.
Next up is this description from Perfect Ban Mario Character Daijiten. Shogakukan, created by the same people who made the Encyclopedia if I am correct. So they would have been given information from Nintendo themself.
"An obstructive pufferfish that swims swiftly through the water. There are two kinds: red and green. You cannot step on them, so avoid them by swimming straight up and down. The red Cheep Cheeps can jump suddenly."
So it seems the intention has been for Cheep Cheeps to be a type of pufferfish since very early on.
This also adds on to the fact that Cheep Cheeps are not harmless, because they bite Mario and friends, they are biting with teeth like Pufferfish do. We know they have teeth because their skeletons have teeth, we see it in Fish Bones. We also see it in Boss Bass(Cheep Chomp) and Cheepskipper(Boss Cheep Cheep).
Now someone might point to the fact Cheep Cheeps don't have spikes, and would question how are they a blowfish if they don't have spikes.
Well you see not every species of blowfish has spikes, but they are still blowfish because they can puff up. This would be the same for Cheep Cheeps.
In addition the Spiny Cheep Cheep species has these spikes, and some subspecies of them seen in Super Mario Land 2 and Super Mario Galaxy can puff up.
