My molly fish is dying, what to do?

[st_baker]

Hello everyone, I'm new in this forum. I've had this male molly fish for almost 2 months, it's the alpha of the tank, it always showed off its fins in front of other mollies but rarely being aggressive to (chasing/attacking) others and other fish seem to respect it because none dare to chase it out. It weirdly has different eyes, one looks normal and the other's black, that's why I call him One Eyed Jack. Today i found out that it keeps swimming in circles towards right direction (the normal eye) and sometimes upside-down as well. I quarantined it for a some time to check it out but i still don't have a clue why. Any idea?

 

[Colin_T]

It has an infection in the brain and is dying. Euthanise it.

Do a 75% water change and gravel clean the substrate every day for a week to dilute any harmful pathogens in the tank.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Try to avoid buying balloon fishes (balloon molly, etc) because they have shortened bodies caused by inbreeding and this causes them to have way more internal health issues. If you want mollies, just get normal ones with a longer body so their guts aren't all squashed up.