Just the one goldfish is too much for this small tank. Common goldfish (single-tails) get over 12 inches, so a tank that is only 12 inches wide, is too small.
The pictus cats are schooling, and you would want to have a school of at least 6, but that's unattainable in such a small tank. Also, pictus cats should not be housed with any goldfish. Goldfish are much like other predator fish, and will try to eat anything, even if it doesn't fit in their mouths, and the barbs on the pictus cats would end up getting stuck in the fish, and both fish could die.
The crawfish will pick at the other fish in the tank. The gouramis are also rather annoying to other fish in the tank.
If I were you, I would get an angelfish, two opaline gouramis (I too, love the look of these fish) and maybe some cory cats (@ least 6.)
If you want to instead go the african route, then I wouldn't get the duboisi. They do best when kept in large groups, but I have come to really like the looks of the Electric Blue Johanni.