Goldfish has strange behaviour

[Tamsin]

My goldfish has been showing some strange new behavior! She has been very quiet, lying still for weeks (after being a very active and friendly fish for the 6 months I've had her). Now she is swimming around again, but strangely. She swims with her head up and tail down. In addition she swims backwards (she swallows water excessively until she floats backwards almost as if she's skydiving out a plane backwards, head first). She is also barely eating, and food used to be her sole joy in life. I thought she may be pregnant again as the last time she lay still for weeks she was making eggs, but this time her stomach isn't bloated and I'm not seeing eggs. I've had a fish pass away from swim bladder disease, and this is not the same behavior he displayed. Any advice out there? Thanks in advance!

 

[DeepAsHadal]

My betta loves food, he really swirls around for snacks. but I learned too much food gives him swim bladder and I have to fast him a few days to fix my mistake. Also check parameters with a full test kit including temperature and that tank flow isn't too strong.