Mbunas are a group of cichlids endemic to Lake Malawi, one of the lakes in the Great Rift Valley in East Africa. When most people think of African cichlids they are thinking of mbunas. Mbuna is pronounced boo-nuh. Many pronounce it um-boo-nuh, but since it is a native African word (meaning rockfish) it should be pronounced the way the natives pronounce it, boo-nuh. Lake Malawi is one of the largest in the world. The lake is over 340 miles long and over 46 miles wide at its widest point. The lake is so large that measurable changes in depth caused by the moon’s gravity are detectable. The lake is also similar to the oceans in that seasonal strong consistent winds can cause upwelling of deeper water, which can alter chemistry, temperature, and nutrient availability. The lake is so deep that only the top one third is oxygenated. Below about 800 feet the water is anoxic. The pH of the lake ranges from about 7.8 up to about 8.5. The ideal pH in the aquarium is about 8.2. The water’s chemistry is also unique among freshwater bodies outside of the other rift lakes in that there are certain minerals and salts present in the water. It has been shown that for these fish to truly do their absolute best, these conditions need to be mimicked. Unless the supply water is hard and naturally in this range, buffers and other hardening and pH raising efforts should be taken. Some have success in keeping these fish without altering the water. Most likely their supply water is naturally hard and alkaline and/or the fish would have done even better under the ideal water parameters. To maintain a proper pH simply use a buffer that will hold the pH at 8.2. Follow the directions on the container. It is better to use a buffer than a directional pH adjuster because the buffer will help provide a stable pH while the directional adjusters can end up causing a roller coaster pH which is more stressful than a non-ideal pH. To provide the trace elements, minerals, and salts characteristic of their native water there are commercial cichlid lake salts. Keep in mid these are not at the same dosage as aquarium salt is usually recommended, they are actually much lower. Many recommendations of salt in freshwater aquariums are about one tablespoon per five gallons. The cichlid lake salt I used had a dose for Lake Malawi of one tablespoon per forty gallons.
The mbunas are elongated fishes with a notably blunt head. They range in maximum size from four to six inches. Their coloration is their main appeal to most people. Their colors vary from solid orange-reds, yellows, blues, white and others to patterns including orange-blotched (OB), vertical black bars, horizontal black lines, and many others. Many people choose them because to the untrained eye they are mistakable for saltwater fish, but do not require the extra expense or effort of a marine aquarium.
There are many regions to the lake. Mbunas inhabit the rocky shallow areas. Large rounded rocks provide shelter and a place for the mbunas’ main diet to grow. They mainly feed on the algae that forms on these large rocks. Included in this are any microfauna in the algae such as small invertebrates. They stick close to the rockwork to avoid the open water piscivores commonly referred to as the haps. They are densely populated in clusters around these ‘reefs’ of rockwork. Any single species can vary drastically in coloration from reef to reef. Many species naturally have a number of natural color morphs that could unknowingly be classified as completely different species if not genera.
Aggression is one major issue with mbunas. For their size they are one of the most aggressive fish out there. There are very few fish that have any chance in a tank with mbunas, but their unique water parameters should prevent any attempts from being attempted in the first place. Their dense populations and lack of safe areas lead them to be very aggressive and territorial. When kept in thinner populations the cost of aggression can be increased since there are fewer individuals in the tank to dilute the aggression. Certain genera of mbunas are more aggressive than others. In general they are all compatible with each other, but it is not a bad idea to stick with genera of about the same aggression level.
A general guide for stocking is one fish per five gallons. So for a 55 you would want to end up with about 10 to 12 fish. However, since you are almost guaranteed to have problems you should start with more. In all likelihood a few individuals will become too aggressive and simply need to be removed for the well being of all the other fish in the tank. In addition to this a few will fall behind in growth and be picked on to a point that it is obvious they will not last in the tank. Rather than let them die you should simply remove them to another tank or find another home for them. Many pet shops are willing to take in unwanted cichlids, but do not expect any compensation. Starting with 15 to 18 juveniles should allow you to end up with goal of 10 to 12 in a 55. Larger tanks will obviously require proportionately higher stocking.
The tank should be setup in a way that mimics their natural habitat. This means it should have a lot of rockwork to provide many nooks and crannies. This will allow them to dart in and out of their shelter as they would in the wild. In addition to rocks, other materials can be used to provide the same result. PVC connectors make for a great addition and the cichlids love them. Ceramic pots can be used as well. They can either be laid on their side or you can use a hole drill to drill appropriately sized holes in the bottoms or sides of the pots. This needs to be done with fine-toothed drills and very slowly. The bit will heat up quickly so be sure to keep an eye on this. You can separate the piles into two or three piles depending on the tank size and footprint. This will allow a better separation of territories, which may help reduce aggression depending on how many males you have and whether you have females or not. To help distribute the weight of all the decorations you can place a plastic light diffuser (sometimes called egg crate) on the bottom glass. Egg crate is a plastic grid of squares. The rocks and other decorations can go through the substrate and rest on the egg crate. This will provide stability and distribute the weight across the entire bottom of the tank, rather than just a few points.
The ideal substrate is sand. It is the most natural. It is also the cleanest. It will not trap debris, which can lead to nitrate problems, but rather keeps the debris on top. With adequate flow and filtration the debris will keep moving until it gets to the filters where they can collect it. Mbunas, like many other cichlids, love to dig. Sand will allow them to do this while preventing their piles from getting too high. It is also less abrasive to their mouths.
Filtration is a major issue with mbunas. Since they are overstocked according to most stocking guidelines filtration needs to increase accordingly. Canister filters will provide efficient and effective mechanical filtration, as well as lots of room for biological media for the increased bioload. Biowheels provide the most efficient biological filtration and help with aeration. However the cartridges are expensive and relatively ineffective. Mbunas appreciate lots of flow, they even enjoy swimming in it like it is a game. Since there is a lot of decorations in a mbuna tank increased flow is good anyways to keep debris moving. Many powerheads have a venturi air intake option. This and/or an air pump with an air stone should be used to help keep oxygen levels up in such a highly stocked tank.
The high stocking levels come in to effect with water quality as well. With so many fish, and inherently so much food, in the tank nitrate levels can rise much faster than in other tanks. This requires a more aggressive water change schedule. It is recommended to maintain at least one water change per week. The amount will vary, but the minimum amount changed per water change is dictated my nitrate concentration. The nitrates need to be maintained at no more than 20ppm. If they rise above this then water changes need to be increased.
Diet can be an issue with mbunas. With their naturally highly herbivorous diet many stick with a highly plant material based diet. It has been shown that too much protein can contribute to Malawi bloat or bloat. This is displayed as a swollen abdomen. However, it seems that it is not simply too much protein, but low quality, hard to digest protein. Hard to digest food can cause digestive problems in many animals, it is just that the mbunas have a digestive system suited to a high plant diet will amplify problems of low quality protein. Like other herbivores mbunas are best suited to many small meals each day, rather than one large meal. This suits their digestive system which is used to constantly taking in small amounts of food. High quality pellets should be the staple of the diet. Many choose to include certain vegetables like zucchini and peas to keep their digestive systems balanced as well as to serve as a constant source of food. This can help keep hunger under control and reduce aggression. Be skeptical of the claims of any fish food. High quality pellets are available at most pet shops and in general you will get what you pay for. There is at least one that has been shown to provide a complete and balanced diet, even when fed exclusively. In addition green algae can be a good thing in a mbuna tank, as long as it does not get out of control. However, with proper maintenance the nitrates should not get high enough to allow the algae to get out of control. By only removing the algae off of the front glass of the tank and leaving it on the backs, sides, and decorations in the tank you provide a natural food source for them to graze on, as well as a subtle natural look to the tank. Green algae, when kept under control, should not cause any negative effects. Its benefits may be subtle, even immeasurable, but can include an increase in oxygen, and a decrease in carbon dioxide, nitrates, and phosphates.
Choosing mbunas can be easy. Almost every pet shop carries at least one tank of African cichlids, usually labeled simply as ‘African cichlids’ or ‘Assorted African cichlids’. Most of the fish in these tanks will be mbunas. Sometimes there will be peacocks and open water haps (both also endemic to Lake Malawi) mixed in so it is a good idea to get an eye ahead of time for mbunas. Many online resources as well as books will provide enough pictures to be able to get an eye for the mbunas as opposed to their lake sharing relatives.
People have had varying success with keeping other types of fish with mbunas. In general they are best left to themselves in a mbuna only tank. They are too aggressive for peacocks, and the open water haps outgrow them and will end up causing problems for the mbunas if the mbunas do not cause them problems. Species that are not native to Lake Malawi will not do well in the high pH and hard water that the mbunas prefer. There are a few Synodontis spp. native to Lake Malawi or other waters with compatible parameters that may do well with mbunas.
Breeding is relatively simple with mbunas. Some species are more easily sexed than others. Some have differing color forms. Females, juveniles, and sub-dominant males will have one coloration while dominant males have another. In other species the number of egg spots on the anal fin are a clue to the gender. Females will only have 0-3 egg spots while males will have 3 or more. If females are to be kept in the tank you need at least two females per male. There is nothing special that needs to be done to induce breeding except keeping them under the proper conditions. When they breed the female lays the eggs on a substrate immediately followed by the male fertilizing them. The female then gathers the eggs immediately in her mouth. The egg spots on a male’s anal fin trick the female into thinking they are eggs. When she goes to gather them he releases more sperm into her mouth to ensure all eggs are fertilized. She will hold the eggs in her mouth until the babies hatch and grow to about a quarter of an inch. She will not eat during this time. A holding female is evidenced by her lack of eating, loss of weight, and swollen throat between the bottom of her gill covers. You can leave the babies with the mother and collect them as they grow in the tank. This will lead to very few making it to adulthood. You can also strip her of her brood. This can be done while they are still in the eggs, in which case you need an egg tumbler. If you wait until they are hatched and almost ready to be released they are larger and easier to rear separately.
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