Fish With Curved Spines

[Fishgirl40]

My swordtail is all of a sudden getting a curved spine so he is almost swimming in an s shape motion. What is causing this? He is still eating and scavenging my tank as he always has. He lives in a 36 Fallon with about 15 other small fish. My tank Ive had for over a year and the water tests fine. Does anyone know what this is? I have one other fish that has the same problem in the same tank along with a silver dollar fish that is now blind. He started off having one eye disitergrate after bulging out and has now effected the other eye the same way. All the otter 13 fish seem to be okay. All of them are eating well.

 

[Munroco]

Lots of fish are very inbred these days and things like spinal deformities aren't rare. It doesn't seem to bother some fish who seem to lead normal lives depite this. With live bearers you need to be careful they don't breed otherwise lots of your fry will have the same problems.