Fish, and especially African Cichlids, should never be purchased on impulse. African Cichlids constitute a large array of almost 600 species, each with unique behavior and differing dietary and habitat requirements. If you randomly and impulsively collect your fishes, then you will learn to regret it and will probably be frustrated with the results. Just because two fishes are African Cichlids from say, Lake Malawi, does not mean that they are compatible. One may in fact be considered prey of the other.
Instead of purchasing your fish from what is available, do your homework; decide what kind of aquarium setup (i.e., decorative look, size and shape of aquarium, etc.) appeals to you and then construct a list of the Cichlids that will excel within these conditions. It would certainly be a mistake to set up a planted tank and then ignorantly introduce a group of Mbuna. You might be shocked to discover that it would only take a few days before these vegetarians raze your entire water garden.
Only once you know what kind of aquarium setup you want and have constructed a list of fish compatible with your setup are you ready to start shopping. I would recommend visiting a few fish stores in your area to see what from your list is available. Then, without buying anything, return home and learn all that you can about these fish to make sure that they are compatible with one another and that they will work in your setup in every other way. This site and the Cichlid Compatibility Chart are great places to start.
Okay, now that you have double-checked your list you are ready to buy. Where to buy? Well, there are many options. The cheapest is not always best: pet store chains are usually the cheapest but fish identifications are almost always lacking or unreliable and the minimum wage staff not very knowledgeable. Plus, the selection at these places is often limited to a few of the more common Mbuna. I am not trying to discourage you from shopping here; I usually get the more common, run-of-the-mill Cichlids here for much cheaper than elsewhere. The next option is your local fish store (LFS). Fish tend to be more expensive here, but the selection is by far greater and the advice more reliable. The third option is to buy from a dealer on the Internet. There are several large businesses on the WWW that have become quite successful. If you have questions about their reliability and quality, check out the Review of Retailers section of Cichlid-Forum.com. Prices online are usually reasonable, but unless you’re going to buy over $150 worth of fish, the shipping charges outweigh the potential savings. If you're purchasing online because you can't find what you really want, well then...that's a whole 'nother matter.
A few final words of advice:
When buying a fish, make sure that the fish you are buying is the fish advertised. If you do your homework, instead of buying on impulse because the fish looks really cool, this won’t be hard. The reason why this is so important, other than the necessity of knowing how to care for it, is to avoid purchasing or accidentally breeding hybrids. Why are hybrids bad, you might ask? Hybrids are bad for several reasons. First, they dilute gene pools for some really gorgeous fish. Let's say you want to purchase a M. estherae (Red Zebra). You are expecting a bright reddish-orange. But, these are often cross-bred, giving a diluted, washed out orange, almost pale pink. Or, if you wanted some other fish, imagine the same scenario. Furthermore, many Cichlids are only exported once or a few times, meaning that if we want to keep them in their original form, we need to maintain their purity. Also, in addition to often producing mottled or pale colors, hybrids may turn out sterile (which would actually be a good thing). Not to mention that most of the Victorian Haps are either extinct in the wild or endangered, which leaves it up to us to propagate these species.
Also, never buy too many fish at once. The nitrifying bacteria in your tank are in equilibrium prior to adding any new fish. Adding fish will set the nitrogen cycle slightly off-balance, but if you add too many, then it will really be thrown into disequilibrium. The ammonia and nitrate levels in your tank may rise too levels that would simulate a new, un-cycled tank, although it will cycle more quickly than otherwise. This scenario could prove dangerous to not only the new fish but to all the creatures in your aquarium. □