Goku was not very active betta from the first day I got him. Few days ago, he started to show sign of sickness. He was weak and he didn't eat for couple of days. So, I took him to the hospital tank and treated him. 3 days later, he was eating and improving. I took him back to his own house and everything seemed to be OK. Last I saw him, he was sitting by the filter which he always did. Next day, he was still at the same spot, but not moving. I got worried so I checked on him. This time, he was gone! I tried to pick up his lifeless body with a net and I couldn't get him. Then I realized his fin got stuck in the filter. I turned the filter off immediately and tried to free his body, but it was really stuck. I had to pull his fin gently so I won't rip his fin off. When I finally freed his body, I realized one of his eye was missing! I felt so bad! Was he still too weak to go back to his house yet? Needless to say, that was the most horrific death of betta I have ever experienced.
I am so sorry Goku. You didn't have to go through this... Rest in peace beautiful!