My Guppy has a ball under its belly! What is it?

[B.H]

Hello, I’m new here.
I just bought guppies the other day and I just noticed that one of the guppies has a lump under the belly. I did some research but couldn’t find a concrete answer to what it is. How should I treat it?

 

[fish48]

it was born with that lump it is known as a conjoined twin/Siamese twins
there is no treatment the fish will live a normal life

 

[Colin_T]

This looks really interesting. Can you post some more pictures of the fish from both sides and different angles, also a video if you can?
Put the video on YouTube then copy & paste the link here.