Why do we need to place a live plants inside the aquarium?

You dont "Need too" it's simply just for the fish to swim through, and hide. It makes there tank more comfurtbale and "homy", if that makes sense.

It's just like putting decorations on your white walls. You dont need too, but it makes your home more interesting, welcoming, and enjoyable.

Or like putting a tv and a couch in your home. You dont NEED too.

Your fish will thankyou if you put some things in there for them. You can even buy cute little castle decorations, rocks, logs, and driftwood!

Good luck, hope this helped.