rare but worrysome behaviour.
I have only noticed this twice in my remaining gold fishwithin the past few months, but when he does it it really scares me.
He will be acting normal, swimming around then he will start to get really frantic shaking his head back and forth Really hard then will jerk a little and go back to being fine, It's not like a siezure though.
He seems healthy other than his head is a little lopsided and dented due to uneven head growth.
I'm getting worried because sometimes he will wack against the glass hard enough to make a loud thump.
40g Fresh water
1 Large Mature Silver Comet Goldfish
4 Bronze corys
1 Apple snail (growing at an alarming rate!)