The reason that Pictus Cats are quite often labelled aggressive, is because a lot of people try and keep them in a tank that is too small, and they try and keep just one of them. Pictus are a schooling species of Cat, and like nearly every schooling species of fish, they will lash out at other fishes, or go shy if they're forced to live on their own.
Pictus are very active fish. The more you have, the more active they will get, but also less aggressive. But as for a good tank size, I would start at a 48" long 70g, and have 4 Pictus. The bigger the tank the better for these guys, as they're very powerful swimmers, and they can sometimes grow upwards of 6". Absolute minimum size for 1 Pictus, would be a 40g long, but even then you'll probably have trouble with the Pictus being aggressive, because he'll be on his own, and the footprint of the tank is still a pretty small area.
I haven't had anything much to do with Convicts, so I'll leave that part to someone else!
If the Convicts don't work out either, and it's cichlids that you would like, there's lots of different sorts of dwarf species that would suit your 46g. And some of those dwarfs will fit into a community set up just nicely, so you can have a nice mixture of fishes.
Three-fourths of the Earth's surface is water, and one-fourth is land. It is quite clear that the good Lord intended us to spend triple the amount of time fishing as taking care of the lawn. ~Chuck Clark