[cypher]

Congrats on getting your first little Russian, he does look adorable.
As mangoandmim said they are best living alone, pairs rarely do well as they are territorial animals & as they mature they want their own space & begin to fight so once he's settled in to his new home he will be happiest living alone.
The cage is quite small & also fairly tall so there is a potential for falls there, do what you can to make sure he can't fall onto anything hard.
Does he have a house or dark place to make a nest in the base of the cage? It's a bit hard to see but they do need a good size house with no base directly on the substrate.
He should be ok in there for a while as he's settling in but you will ideally need to upgrade his cage.
The hamster heaven cage is a fairly good size & not too tall, best used without the tubes & penthouse though! The large front door is a big bonus making access really easy.