Oh, hello then!
I'm not very familiar with those Juwel Rio Aquariums. The 450 liters of water volume sounds promising, at least. I will ALWAYS advocate for larger aquariums when stocking with New World Cichlids
But, the often biggest concern when stocking with Cichlids, is often NOT the volume capacity of the tank itself.
Nope.
It's the bottom dimensions, or 'foot print' of the tank. That size determines how much actual room your fish stocked in the tank will have to swim freely, turn around in and to hold and defend territories. Cichlid species known for being relatively peaceful, can become extremely pugnacious when stocked in tanks too small to properly accommodate them with other fish. :x
The 151cm X 51cm dimensions of the 450 liter aquarium look pretty good to me, and the taller 66cm height will be appreciated by your Uaru (If you decide to stock with it). I would recommend stocking with a group of 'mini-sized' Geophagines for this tank, as the larger-growing Earth Eater species will appreciate a bit more bottom space than this tank will provide, if stocked in a group. This recent posting thread may help to inform,
https://www.cichlid-forum.com/phpBB/vie ... 0&t=453535
Good luck with it, and this sounds like it will be a very nice aquarium. 8)