I have a shoal of white cloud mountain minnows which have been living in harmony with my goldfish for about 2 years now. The males fight amongst themselves as males do. However today I've found one of my minnows that is unable to stay buoyant, it's grounded on the bottom of the tank. It's the 3rd one i've found like this in a matter of months. Are these minnows the ones that have lost the battle with their rival male and fighting has ruptured its swimbladder? (My goldfish are indifferent to the minnows and show them absolutely no interest. The minnows have shown no signs of illness ever. All my goldfish are healthy too)