My Betta boy

[Kovathepit]

Hi I have this big blue Betta boy who is a little large but very active for awhile he was living in a 10 gallon tank with some guppies and surprised me that he was gentle. I removed him and put him in here because the guppies were pestering him and his long fin so he started to pout. I gave him company with his favorite female Betta.
My question to you is there anything known for why he looks like a baby hippo ?

 

[Autumnsky]

It looks like Pine-coning / Dropsy, which describes the effects of an infection and isn't one disease. It is an internal infection.

It looks severe.

You can try keeping excellent water quality along with medication
https://www.seachem.com/kanaplex.php