The main issue at hand, and this gets repeated on nearly every beginner African thread, is that they don't get really aggressive until sexual maturity. Bumblebees are incredibly aggressive as adult. It WILL kill a cory cat eventually, not to mention that cories require soft, acid waters, as well as groups to thrive. Africans like hard, alkaline waters. The green spot puffer WILL get stressed to death or killed, they are very difficult to keep in pure freshwater at ANY age. Tetras WILL eventually become snacks to fish that are naturally algae grazers (minus the bumblebee, which are known to be more omnivorous). Also, feeding ghost shrimp to rift lake cichlids is less than ideal. Just because they can eat something, or will eat something, doesn't mean they should. Just because your child will eat candy, doesn't mean they should eat it, right? The last thing to address is the jewels. While yes, they're African, they are actually WEST African, inhabiting rivers that are soft and acidic, rather than the hard, alkaline Rift Lakes. Although many people add them to Rift Lake tanks, they really don't belong.
The intention is not to attack you, but rather better you as a fish keeper. Research is the most important thing.
With Africans, the aggression is an awfully difficult thing to deal with, especially when mixing lakes, or even groups within each lake, like how Malawi has mbuna, peacocks, and haps. Similarly, you don't want to mix certain tanganyikans, like putting frontosas with shell dwellers. I know even my 1" neolamprologus multifasciatus (shell dweller; smallest known cichlid) are quite aggressive and protect they're fry quite strongly, killing ghost shrimp, and although I don't add fish, they'd kill any if I did try it. And that's just a 1" fish!
