The first thing to consider is what type of fish do you want to keep. Lake Malawi is so big that it offers many types of habitat and each niche is filled with its own type of fish. The most popular of these are the Mbuna, because of their bright colours
Lake Malawi
Lake Malawi is the third largest lake in Africa and the ninth largest in the world. It used to be called Lake Nyassa, and it is surrounded by three countries – Tanzania, Mozambique and Malawi. It is almost 375 miles long and has a maximum width of 50 miles. It has a depth of 700m in places but the average depth is 292m. The average pH is 7.8 to 8.6, but surprisingly the GH is 4 to 6 and the KH is 6 to 8, making the water very soft. The temperature at the surface varies from 23 to 28C. Because of the size and the huge volume of water involved the lake is very stable, and the fish that live there have become accustomed to this and generally they need to be kept in a stable environment if they are to thrive.
The lake has over 600 known species of cichlid, many of them endemic to Lake Malawi (which means they are found nowhere else). There are many habitats, from boulder strewn shores to open sandy areas, Vallisineria beds to deep open water. The fish, known locally as ‘mbuna’ (rock dwellers), are extremely colourful and are highly prized by aquarists. Some of them can rival marine fish for colour. They are all mouth-brooders, which means that they keep their eggs and young fry in their mouth until the fry are big enough to care for themselves. They are also very aggressive, but this can be overcome by correct care.
Tank
The tank should be the biggest possible. This is because it will be easier to maintain stable conditions and it will give the fish enough room to escape a bully. The smallest size you should consider is a 48″ x 15″ x 15″, and in such a tank you would have to limit your choice of fish to the more gentle less aggressive species.
Filtration
A good powerful external power filter is the best option for mainly biological and mechanical filtration. Under-gravel filters are not much use because these fish constantly dig and would short circuit the filter. These fish demand clean high quality water conditions. Ammonia and Nitrite should both be 0, and Nitrate must be kept below 20 ppm. This means routine water changes are essential. With mbuna there is a lot less aggression when the fish are kept slightly crowded, which in turn means that any filter should be big enough to cope with the higher than usual demand.
Substrate and decor
The substrate should not be too deep or it will trap dirt and adversely affect the water quality. 1/2″ is plenty and it should include some coral sand which will act as a buffer and help to maintain the correct pH. Other open water species prefer sand which they will sift through looking for food. Mbuna must have LOTS of rockwork in their aquarium but open water species don’t need any rockwork. If you use rocks in the tank make certain they are stacked safely. Use aquarium grade epoxy resin to bond the rocks together and put the rocks in place before adding the substrate, so that the fish can’t undermine them. All types of rocks can be used, including calcareous rocks – these will in fact be useful since they will help buffer the water and keep it stable.
Water Chemistry
These fish have evolved in a very specialised way to be fully at home in a certain set of conditions over tens of thousands of years. Whilst some of the captive bred fish have become more tolerant of a wider set of conditions they are still at their best when kept in the conditions they have evolved to best cope with. The water in Lake Malawi is hard and alkaline, and whilst the hardness isn’t critical the alkalinity is. They need a high pH: 7.5 to 8.4.
Feeding
All mbuna will do very well on a herbivore diet with occasional live or frozen food added. In the wild they graze on algae and any small creatures that live amongst it. This has become widely known as Aufwuchs. In order to replicate this they need a light high fibre diet. Suitable foods include Spirulina flake, vegetarian flake, daphnia, algae, thinly sliced cucumber, lettuce, cyclops, daphnia and bloodworms. They should be fed little and often, 2 or 3 times per day
Note: It is important not to rely too heavily on dried food because this has been linked to a condition known as Malawi bloat, which as the name suggests causes the fishes’ bodies to swell and can result in death. Also, these are greedy competitive fish with a strong tendency to over-eat, which results in obesity. Fish that become obese will have shorter lives as a result.
The Fish
When selecting the fish for your tank there are some general rules which will help keep things go smoothly:
- Keep only one adult male of each species with two or more females.
- Don’t keep very similar or closely related species together.
- The stocking level is absolutely critical – if there are too few fish there is a very real chance of one of the larger males becoming hyper-dominant and attacking all the other fish to the point of actually killing them. Too many fish will lead to stress from over-crowding, which in turn will lead to ill health. In between these two scenarios is the ideal, where there are too many other males for a single fish to risk trying to become dominant but there is still enough space to allow them to feel settled. This is what to aim for. Generally if you allow one inch of fish for every eight sq. inches of water surface you will be in the right area for the stocking level. But that is only a guideline – it will depend on the individual set-up and fish concerned. Personalities even vary from fish to fish, so it may be necessary to intervene at some point until you finally reach a peaceful tank. Under no circumstances should you try to keep or breed these fish in a breeding tank using a single male and female. This will nearly always result in the female’s death.
This is only a very limited selection as there are some 600 known species and most of those have a variety of morphs:
- Iodotropheus, one of the more peaceful species.
- Labeotropheus, keep only one male per tank.
- Labidochromis, also generally peaceful (for mbuna).
- Metriaclima, an offshoot from pseudotropheus.
- Melanochromis, very aggressive.
- Pseudotropheus, aggression varies from species to species.
Breeding Mbuna
If these fish are kept in good conditions and free from stress they will breed very freely in the community aquarium. Most species are extremely prolific, and good healthy colourful young are very much in demand. What is more, the fry are very easy to raise. Having said all that, I imagine you might be wondering why these fish are listed as being more demanding to breed and not in the easy section. The reason is that they need a specialist set-up in order to keep them, and they cannot be kept with other fish due to their special requirements.
Selecting the parents
The fish will choose their own mates. To ensure good quality fry keep good quality stock. There should be a ratio of one male to two females, and for the more aggressive species one male to four or five females. Only one male per species should be kept per tank and even similar looking species are best kept apart. Sometimes hybrids occur – if this happens they must not be passed on or sold, because such action would eventually ruin the captive bloodlines of these fish to everyone?s detriment.
Preparing
Maintaining healthy well-fed fish is all the preparation that is needed. The males are constantly on the lookout for a female that is ready to breed. The males will hold a small territory, and they will display vigorously to any passing female. If the female is ready to breed, the pair will circle each other and the eggs will be laid. As this happens the female will collect up all the eggs and hold them in her mouth in order to protect them.
During this time she will not eat and she will lose some condition. The brooding females are easy to spot because they tend to be thin and the brood pouch can easily be seen in the region of the fish’s chin. The eggs and fry will be protected in this way for about one month. Once the fish have bred, wait for a few days to allow the female to bond with the eggs and then transfer her to another aquarium with the same water chemistry and temp. so that she can be on her own. The tank will need a mature sponge filter and some stones with a little cave so that the female will feel secure. Don’t offer any food during this time, particularly with inexperienced fish, or the eggs and fry could be put at risk. When the fry are old enough they will be released, and in most cases that is the end of being protected. The mother should now be removed from the tank or there is a risk the fry could be eaten.
Even if left in the main tank, some fry will grow up provided that there are plenty of nooks and crannies to hide in, as this one inch Melanochromis auratus shows.
Rearing
This presents no problems. The fry will eat finely powdered flake food and newly hatched brine shrimp. They will also browse on the surface of the sponge filter and on any algae present. After two weeks you can begin to make small daily water changes and gradually increase the amount until after five weeks about 20% daily is being changed. These water changes are every bit as important as feeding as far as the fry?s progress is concerned. After ten to twelve weeks the fry will be ready to sell on at just over one inch.
Author
Images
Andy Gordon
John de Lange
First Publication
Fish, Tanks and Ponds 2002 – 2004 All Rights Reserved
Source
Aquarticles (no longer available)
