unwell leopard danio

Question
One of my Danios has begun to struggle to swim upright, body drifting below head height and resting a lot on its side.  His spine is curving downwards too.  I had another do something similar, then die, about a year ago. I've isolated him. What is he suffering from and how can I treat him?  

Answer
Hello,

This sounds like an internal bacterial problem. I recommend treating with a product called Maracyn-2. If this heals him and his spine is still curved, he may be deformed or have a more serious disease. If this is the case, don't hesitate to contact me again and I will see if we can diagnose the cause of his curving spine.

I hope this helps.

Regards,
Stephanie