Guys need help. I have a 5-6 inch fish that every hour has started twitching and swimming around the tank in circles erratically, hitting the sides and looking distressed.

Water perimeters are normal. No nitrates/ nitrates. PH 6.5, 31degress. They are wormed every month, 25% water changes Tuesday and Saturday.

I have run a course of octozin but there isn't any change, thinking it may be an internal issue.

Please help folks