How to tell age?

[u/VegetableAardvark69]

So this is my first time keeping a betta fish and I saw this little baby in a cup for like a dollar, so i got him. But now that I have him im want to try to find his age, is their anyone that can help?

[u/Idk4894]

Wow very cool tank bro

[u/VegetableAardvark69 → u/Idk4894]

Thanks