is my betta's tail in poor condition

[flumen]

I really need help with this, can someone pls tell me what I can do

[coltin]

First things first, you gotta check your water quality - ammonia, nitrite, nitrate, and pH levels.
You're gonna wanna do a 75% water change, and gravel clean that substrate every day for 2 weeks.
Also, make sure any new water you add is free of chlorine and chloramine.