odd

A couple of month ago my friend had to move and gave me his tiger barbs. I had already had tiger barbs so I knew what they needed. One in particular looked very ugly and had a big belly and my friend said that the fish had that belly since it was a baby. I let it go. Today in the morning it was...

Hi,   I have just come back from my local tropical fish shop and started acclimating my new fish when i realised that i have an odd fish, it think its a tetra but it is on its own as it was in a bag of ottos can someone tell me what to do???   Thanks in advance  

So, I've heard much info on this and wanted to know the general TFF community's view. Thanks!