If you are new to cichlids, especially African cichlids and more specifically mbuna, you should rarely be surprised when you find one of your fish upside down in your tank looking like it got drug across the driveway. Cichlids fight, get picked on, and get killed by other cichlids. Know this before you set up a cichlid tank.
If I’ve said this once, I’ve said it 1,000 times. Do your homework before you buy your first cichlid! If you don’t, and unless you plan to keep only one specimen, you WILL lose fish from aggression. Worst of all, you’ll not understand why you have a dead fish when you wake up in the morning, despite your water “being perfect” or “all parameters are fine.”
Almost all cichlids are territorial by nature. Like you and your own home, cichlids don’t want other fish coming around their abode and swimming through their living room uninvited. Unlike you and your home, which presumably has an exit to the outside, fish tanks don’t have exits (except via an uncovered top). There is limited space to retreat to, especially if nearly all space in the tank is spoken for by another fish. This is why you often see fish near the water surface hanging behind a heater or a powerhead. That is the only place they can go to get away. Eventually, that will wear on the fish, and it will die of disease or still get attacked and killed.
If you don’t do your homework, you don’t learn about the fish before you purchase it, and you don’t understand what other cichlids might be compatible with it, then be prepared to net dead fish out of your tank. It will happen and it will be your fault for not educating yourself beforehand.