white belly

Hi, First time here and was hoping for some help with my Betta. He unfortunately wasn't that well taken care of for a while and developed a large white streak on his underside that I wasn't initially sure what to do with. I increased frequently of water changes (once every 5-7 days with his...

I have two black mollies and one seems have bigger stomach. Not sure whether it's pregnant or over fed. It has white spot on the stomach but swims as fast as the other one. It also has a fin just above the anus and two small fins on the sides. I am not even sure whether it's a female. Should I...