Cardinal fin problem

[craig110768]

I have a banggai cardinal fish that has been in my tank for over a year. I have added no new fish recently.
Last night I discovered that most of his fins had been eaten off. Not sure which fish would do that - I did notice that my squiriel fish had now started to chase him - not sure if that was the fish that initially bit off the fins though.
Do fish do this if they are not getting enough food? I feed them one cube a day. F1 and F2
The cardinal fish has now died.
Any comments.
Craig

 

[bang guy]

Just a theory that could easily be wrong:
How old was the Banggai when you got it? If it was wild caught it's possible you received an old fish. They are not long lived like Tangs. 7 - 10 years is it as far as I can tell and it may be even less. The Squirrelfish may have sensed weakeness and started chasing the Banggai.
Onother though goes in line with yours. They are not aggressive so it may not have been getting a full ration of food.