Tiger Barbs!!!!!!!!????????????!!!!!…

Hi! Well, I was looking at one of my Tiger Barbs, and it has a rounded belly and a black spot on the side. He/she never looked like that before. They have grown and are now Large tiger barbs but when I got them they were small. Do you think it might be pregnant? I haven't been able to watch it for this past week because I have been moving so I kept them at my old house. Today I got them over to my new house and I just noticed this... should I be worried? I have four of them...