Is this anything to worry about?

[Pleco-Heaven]

Hello, about 4 of my tiger barbs have an internal Red line just on the outside of the belly near the anal fin, but when they turn around, the line is black. Also there is a protuding bump just below the pectoral fins, making the body straighter with corners around the belly, unlike the others who are more rounded. Could this be a disease? Breeding season?

Thanks for any useful information!
Pleco-heaven.