I've had my betta Ophelia for a year and a half. For about a week she has been much less active than usual, and for a few days she hasn't been eating. (I changed her water this Sunday. There's a heater in the tank and the thermometer is reading at just above 80- as usual.)
For the past few days, I've been putting in betta fix and trying to feed her a pellet every day (by putting it in right near where she is swimming). At first she ignored it completely. Yesterday she tried snapping at it but didn't get anything. Today she is looking more active but ignoring the food again.
I haven't noticed anything that looks like fungus on her body. Her color is very pale at the moment, probably for lack of food. I can see a gray spot around the top of her mouth, but it's not big or raised. Could that be mouth rot? I've read that tetracycline or other antibiotics can be used to treat this- but is there any risk if that's not it?
She did have one bout of not eating this winter, but I think that was because I didn't have a heater. After getting the heater and giving her betta fix she recovered.
Please help! Thank you.