My Cherry Barb with swollen belly

[maverick786us]

Some of my cherry barb have developed this swollen belly, do I have to worry? They look active and healthy and not lethargic. I did some research on google and I hot the result that poor water quality is one of the reasons. But in my case the water quality isn't poor. I change 40-50% water every week and I have good filtration system.

 

[G H Nelson]

They look fine and healthy!
Females.....are rounder-bodied than males.

 

[maverick786us]

They look fine and healthy!
Females.....are rounder-bodied than males.

Thank you, is breeding cherry barb difficult