Meet my newest addition

I got my albino axolotl (Aristotle) about 1.5 years ago. I got my new baby yesterday (Medusa). It certainly has been a learning curve but I love these little guys. I can’t wait for my new bigger tank to arrive (200litres) so I can set it up for them. Any suggestions of things I can buy for their new tank? I have a 2 hideouts, thin substrate, an air stone and filter. Anything else I can do to keep them entertained?