Just got this new boy two days ago at Petco, and I noticed this one little split in his tail but it looked natural to me. However two days later it's looking a little bigger, and i'm wondering if it could be fin rot? Or tail biting...I'm not sure how to tell the difference. and any suggestions for treatment?
all other behavior seems normal, he flares at his reflection, follows my finger, is eating normally, etc etc.
I feed him a diet of betta pellets and the occasional freeze dried bloodworm. His tank is filtered and heated at 80 degrees. His water was tested at petco two days ago and deemed "all good." (As far as that can be trusted). I use seachem water conditioner and stress zyme.