Is this betta behavior normal?

I have had a crown tail male betta for about a year now, he lives in a 15gallon tank with 2 corydoras and some different types of snails (nerite, bladder snails and ramshorn). Last time I tested these were the water parameters:
Nitrite:0
Nitrate:0 (I think I need a better test for this as i don't think it works)
Ammonia: 0
Ph: 6.8

When I first got him he was really active and curious but he has grown a lot since i first got him. He now sometimes just sits/floats about in the same place for 5-10mins without doing anything. I'm assuming it's down to his big fins but just wanted to check that he wasn't unwell. He is still eating fine and is still swimming fine too when he isn't resting. So is resting for up to 10mins normal for a betta? (Sorry if this is a stupid question but don't want to miss a sign of illness)
Thanks in advance!!

Also I know that corydoras should be in bigger groups but I'm planning on upgrading the Cory's to a bigger tank with more friends at some point in the future as the betta has began to flare at them recently

 

Sounds normal to me. Bettas do like to rest every so often.

 

Thank you so much!

 

He may just be watching his tankmates, too. My betta does that a lot.

 

Maybe he’s getting old and tired, so he sits back in his rocking chair and watch the kids play ..