Betta and Moon Rock

Hey guys! I'm starting a tank for a betta and am wondering about adding a Glo Moon Rock to the tank. There are two bigger holes about 3 and 4 inches in diameter, but there are two that are only two inches around. These holes I can stick my finger through, but I'm worried about my betta getting stuck like the bettas that get stuck and killed in the bottom holes of terra cotta pots. If anyone has feedback, please let me know! Especially if you've had a Glo Moon Rock in with your betta. Thanks!

 

Omg! I have these in mine! Agh, I wanna know about this question to! I don't want him to get stuck! I didn't k ow that could happen! (obsessively watches over him)

 

I've heard that any holes should be the size of a quarter, but I should think that if an adult thumb can fit easily that it's probably fine.

 

I... I have baby hands... *yells frantically* Dad! Dad!

 

Or you could just grab a quarter