My Java Fern is very healthy and continues to grow nicely which is great. It's a nice full size but it's mainly full because the leaves are floating out if that makes any sense. I want to bunch it together in some kind of way to reduce how wide it is. My question is what can I use to tie it together to reduce the width and is also safe to use in the aquarium?

Not looking to thin it out because I don't have anywhere to move the extra ferns to in this tank or anywhere in my other two tanks.