Thread title went wrong on the original!
So GP1, who outlived two others, was fine yesterday morning. In the evening he went downhill and of his food and died late last night 
He had a good life and brought us a lot of pleasure. I'm assuming it was simply old age as he was 5.
Gp4 is 2. He's always looked to GP1 for reassurance. We left gp1 in their cage but gp4 got distressed pushing him around trying to to rouse him 
How soon do we leave it before getting him a new buddy? I think he's going to be very anxious on his own.