Your Goldfish did this, DO NOT put him back with the goldfish unless you want him eaten next time!
For yrs I tried to keep betta's and other smaller fish with goldfish.
Things are usually ok as long as your goldfish are small,
But once they start to get bigger (which isn't very long at all, they will become a serious problem for your small fish.
If your smaller fishs "such as a betta" is flighty around goldfish they tend to survive longer,
The first time I had it happen I really didn't know what to think, Until I actually caught the goldfish eating the smaller fish.
I have goldfish here now that about 3 months ago I had to seperate, They just one day started,
The swimm along with their mouth going like they are half blind and will try to eat anything they can get in their mouth.
Just not A good idea to keep a betta with Goldfish, Their finnage alone makes them slower then other small fish, I'm really surprised all he lost was his finnage and not get devoured.
Last edited by Chicklet; 03-20-2010 at 10:00 AM.