I have had my tank for over a year and i introduced a Betta 2 months after so it had a chance to develop. Once i introduced it the fins on the fish started to rot away. Being new to all this i left the fish in the tank but kept a close eye on it. The fins rotted back to a certain point and then stopped so i thought all was ok.
The fins would start to grow back but when i completed tank maintenance and cleaned the filter and did a water change the fins would fall away again but only ever back to the same point.
I had the betta for 10 months and it recently died so i took my tank water to my local experts who completed a Ph, nitrate and nitrite check and they told me i was perfect so i purchased another betta. I told them what had happened previously so they advised completing a course of Myxazin, which i did. I have now completed the course but my betta has still lost 60% of his tail but he seems happy enough and is having fun bullying the smaller fish in the tank.
What can i do to get him back to his former glory and does anyone have an idea as to why this keeps happening to me when i have what i thought was a perfect balance in the aquarium?
All help would be greatly appreciated.