Betta Fish: Introducing my new betta

I bought him yesterday! I hope he likes his new tank (it's a kinda blackwater walstad 25L/6.6g tank).

I'm a bit worried as his tail looks shorter and less developped as the rest of his fins. Is this normal (he looks also quite young and small so I guess it could still be growing?) or could it have been teared/is it fin rot ?

I'm also open for any name suggestions! So far he has been very active, curious and easily distracted (apparently he can't focus on anything more than two seconds even food xD) so I was thinking something a bit silly.

Also if anyone know his color/tail pattern, I'd be grateful to know! The only thing I'm certain of is that he's a male red crowntail 🙂

The first picture is from yesterday and the rest from today.