African Cichlids – The Rock Dwellers

African cichlid species make up an astonishing group of animals with great diversity in terms of colors, preferred habitats, prey and behavior. While one can encounter cichlids in small lakes and rivers, most of the species inhabit three great African lakes: Lake Malawi, Lake Tanganyika and Lake Victoria. Consequently, African cichlids are classified in three big groups according to the lake they inhabit.

Lake Tanganyika and Lake Malawi were formed along the separation of two tectonic plates when two valleys were filled with water some million years ago. These ecosystems, known as rift lakes, host a stunning variety of cichlid species: Lake Malawi alone hosts around 800 species most of which are endemic to the lake, meaning that they cannot be encountered in any other place in the world, while Tanganyika hosts around 250 species.

The three African lakes, despite having discrete characteristics display similar environmental conditions concerning water quality. All three of them have an alkaline pH and a high load in salts and minerals, as most rivers that reach them are highly mineralized. Providing hard water (i.e. with a high concentration in salts) and maintaining a high pH (8-8.5) is important in order to maintain African cichlids in the aquarium. Lower pH will increase the susceptibility of the fish to disease, and might cause coloration loss. Maintaining an alkaline pH can be achieved by purchasing special chemical solutions and keeping shells, coral pieces or coral sand in the aquarium. The temperature of the tank should also be stable, maintained at 75-80 °F (24-27 °C). It is also important to regulate the levels of ammonia produced by the fish, as it can be toxic in environments with such high pH levels. This can be done either by regular changing the water or by following more advanced techniques such as the fishless cycling.

Although there are several African species with a variety of preferences in terms of habitat, many of them are rock dwellers. As a result, adding rock and boulders that will provide several hiding spots will enhance fish health and well-being. Providing hide-outs can also be a way to regulate fish aggression. Many of the African cichlids are large, school forming fish, but can be extremely aggressive to other species. It is thus important to choose the appropriate tank size, taking into consideration not only the number but also the size of the fish, as bigger species will generally need more space.

African cichlids also have a varied diet, including both predators and herbivores (plant eaters). For school forming species it is important to provide enough amount of food several times per day, as there is a high level of competition for food among individuals. However, overfeeding the fish will have adverse effects for their health, such as the syndrome of “Malawi bloat”, in which fish present unexpectedly big bellies. Consequently, the best strategy is to split the usual amount of food in several smaller portions that will be given throughout the day.

Overall, African cichlids are a spectacular choice for aquarium lovers, as they are easy to keep and provide a wide range of colors and behaviors that compensate more than enough for the effort required by their maintenance.

South American Cichlids Overview

South American Cichlids, or “new world cichlids”, are a group of colorful, durable species which although not as famous as African cichlids, they display a remarkable variety of shapes, colors and behaviors. An estimated number of 450 cichlid species can be encountered in rivers and lakes of South America, however 75% of the known species can be encountered in a single river, the Amazon.

Cichlids can be encountered in a variety of habitats in South American rivers, mainly classified according to the predominant water properties. Clear water rivers (or blue water rivers) have a dense substrate that is hard to dissolve and thus doesn’t release sediment to the water column. Such rivers allow the growth of plant species and have pH between 6.9-7.5 and hardness between 5-12 dH. An example of a clear water river is Rio Xingu, which is known for its rheophylic species, i.e. species that usually inhabit rivers with a high water flow. White water rivers on the other hand, have a lot of suspended sediment in their water, which creates a slightly acidic environment with a pH around 6.7-7.1 and a dH between 3-5. Due to the high turbidity of the water, light does not penetrate and one can hardly encounter aquatic plants. The Amazon river is the most famous white water river, hosting however one fifth of the world’s freshwater fish (around 2000 species). Lastly, black water rivers have a very high load of organic matter, due to the decomposition of leaves, seeds and other plant pieces that fall from the trees forming the dense tropical forests which surround these aquatic ecosystems. This creates an acidic environment, with a pH around 6 and surprising dH levels which normally are close to 0, due to the lack of minerals. Commonly to the white water rivers, aquatic plants are not usually encountered in these habitats. A famous black water river is the Rio Negro, where one can find the beautiful Chocolate cichlid.

Cichlids from South America can be classified in three main groups: Angelfish and Discus, large American cichlids, and Dwarfs. The first group is comprised of spectacular species in terms of color, shape and behavior. Most of them have a disc-shaped body and many species display incredible behaviors: many aquarists confirm that angelfish usually play with the aquarists which they seem to recognize, even getting food from their hands. The second group of species, is comprised by large predators which need large tanks (at least 70 gallons-250 L) and are also famous for their very friendly behavior towards the aquarist, with some species being characterized as the “real pets”. On the contrary, dwarfs which consist the last group of North American cichlids are small, shy and very delicate species.

Keeping South American cichlids in an aquarium is not a difficult task, however it requires sufficient planning. The first thing to take into consideration is the task, which will define the tank size. Creating a small cichlid community will require a larger tank than maintaining a couple for breeding purposes. In the case of the community, the species should also be selected properly. Large South American cichlids might be aggressive, especially when overcrowded in a small tank. Plenty of rockwork would provide refugee for smaller fish and would be a way to protect them. Moreover, plants should be adequately fixed to the bottom of the tank, as many species will uproot them. Aquarium glue could be used to glue the plants into small pots and bury them in a layer of gravel.

References

Axelrod H.R. 1993. The Most Complete Colored Lexicon of Cichlids

Stratton R.F. 2002. The Guide to Owning Cichlids, T.F.H. Publications, Inc.

Ulrich Glaser, Wolfgang Glaser. 1996. AQUALOG: South American Cichlids I-III

Lake Victoria Cichlids – Little Colorful Survivors

Lake Victoria is the second largest freshwater lake in the world and one of the youngest lakes in Africa. Despite its young age, it hosted a remarkable number of species which has attracted the interest of many scientists studying fish evolution: the lake had been characterized as an evolutionary miracle, hosting a variety of species including more than 400 cichlids.

Unfortunately, this is no longer the case as a great number of species have gone extinct due to an ecological cascade that caused the collapse of Lake Victoria’s ecosystem. The problems started with the introduction of two non-native species, the Nile Perch (Lates niloticus) and the Nile Tilapia (Oreochromis niloticus) in 1950. The Nile Perch, being a vicious predator of great dimensions, heavily preyed on all smaller fish and led most of them to extinction within 50 years.

The disappearance of all herbivore fish species leaded to an incredible increase in phytoplankton and consequently in bacteria, which feed on dead phytoplankton biomass. Such bacterial blooms, usually consume all the available oxygen and lead to a phenomenon known as eutrophication. The problem was enhanced by high levels of pollution originating from nearby cities and deforestation of the native vegetation in the lake shores, which lead to the overexpansion of a floating weed-species known as water hyacinth. The increased biomass of the latter is a further food source for bacteria, deteriorating the water quality even more.

The destruction of the lake ecosystem had devastating consequences for the cichlid populations, leaving only 200 Lake Victoria cichlid species. Some of the latter are maintained and breed in aquariums, in the framework of rescue programs aiming to prevent further extinctions. As scientists focused on potential solutions to the ecological problems of the lake, there are few studies on the cichlid species of the lake and as a result Victorian cichlids are hard to identify.

While not as diverse as Tanganyika cichlids or Malawi cichlids, the lake hosts remarkable specialists both considering food sources and habitats, e.g. some species are specialized in stealing eggs from the mouth of cichlid females who display the behavior of mouth-brooding. Some Lake Victoria cichlids can be extremely aggressive, as is the case with all African cichlids. Due to the variety in the size and aggressiveness of the species, single species tanks might be advantageous. Care should be given to provide the appropriate tank size and substrate according to the species preferences. The tank temperature should be maintained around 76-77 °F (24-25 °C), however, as the lake is not as alkaline as other African lakes, the pH should be kept around 7-9 and the hardness around 2-8.

References

Kocher D. 2004. Adaptive evolution and explosive speciation: the cichlid fish model Nature Reviews Genetics 5, 288-298

Axelrod H.R. 1993. The Most Complete Colored Lexicon of Cichlids

Darwin’s Nightmare by Hubert Sauper. film release: 2004

Lake Tanganyika Cichlids – A Stunning Diversity of Freshwater Fish

Lake Tanganyika is one of the oldest and largest lakes in the world. It is also the second deepest lake in the world, having a depth of approximately 4823 ft (1420 m). It hosts more than 150 cichlid species belonging to more than 50 genera. These species are classified in twelve groups, eight of which are endemic to the lake.

Lake Tanganyika cichlids display a surprising variety in terms of body shape, preferred habitat, prey and social behavior. This is due to the great diversity of habitats that can be found in the lake, which allowed the evolution of many different species. The shorelines of the lake and especially the upper zone of the water comprises the surge zone, which is rich in oxygen and plankton and is the unique habitat where gobby cichlids can be found. The rocky shores of the lake, with their steep drop-overs and strong zonation provide different micro-habitats for a variety of cichlids, including mainly small species with strong color patterns that allow them to camouflage in between rocks, as is the case for the frontosa cichlid (Cyphotilapia frontosa).

Sandy bottoms host a number of sand dwellers which scoop the sand in order to find their prey. Some of these species display schooling behavior while others hide in snail shells which can be found in great numbers at the lake bottom as the high levels of calcium prevent their decomposition. Muddy bottoms, poor in oxygen but rich in organic matter provide food to bacteria and subsequently small invertebrates which consist the perfect prey to cichlids, adapted to these extreme conditions. Lastly, the large water column hosts a number of zooplanktivorous and piscivorous schooling species, feeding on zooplankton and fish respectively.

Because of this stunning diversity, which is unique among African cichlids, species from Lake Tanganyika are extremely famous among aquarists and fish lovers. Their maintenance in the aquarium requires a stable temperature between 76 and 78 °F (24 and 27 °C), a pH between 7.5 and 9.3 and hardness between 10 and 12 dH. Selecting the right substrate for each species is very important and food type strongly depends on the species.

Moreover, some Tanganyika cichlids can be extremely aggressive towards each other, or towards other species. Consequently, a research on species requirements is highly recommended before selecting the species and setting up the fish tank.

References

Konings, Ad. Tanganyika Cichlids. Holland: Verduijn Cichlids, 1988. Loiselle, Dr. P.V. The Cichlid Aquarium. Germany: Tetra Press, 1994.

Lake Malawi Cichlids – A Group of Colorful Unique Fish

Lake Malawi is one of the oldest and largest lakes of the world, known for the clarity of its waters and the fascinating amount of fish species that it hosts. It is estimated that it hosts around 1000 species of fish species, only a third of which is scientifically described and catalogued. Apart from 44 fish species which belong to other families, all the rest are cichlids. Moreover, more than 99% of these species are endemic to the lake, meaning that they can’t be found anywhere else in the world, while there are also fish endemic to particular islands or areas of the lake. The colorful cichlids of Lake Malawi are classified into two main categories: Mbunas and Haps.

Mbunas are rock dwelling fish that inhabit the rocky shores of the lake. The group consists of ten genera: Pseudotropheus, Melanochromis, Labidochromis, Petrotilapia, Cynotilapia, Cyathochromis, Genyochromis, Gephyrochromis, Iodotropheus and Labeotropheus. These cichlids normally live in groups but are not considered schooling fish and are quite territorial, especially during the breeding season. Their aggressiveness is usually towards conspecifics, i.e. similar fish, and can be regulated either by providing food several times during the day or by overcrowding the fish tank.

This technique rather distributes the aggressiveness of the dominant males to several males and needs caution, as the water needs to be changed regularly and the female to male ratio has to be maintained to a minimum of 2:1 in order to avoid problems with increased organic matter (i.e. material produced by the fish) and increased male stress respectively. Moreover, creating a rocky habitat within the aquarium is extremely important, both for breeding reasons and in order to provide hiding spots for smaller individuals, which are prone to the bullying of larger cichlids.

Mbunas, like most cichlid species, are mouthbrooders and require space for their breeding behaviour. Lastly, Mbunas are mainly herbivores and possess a short body allowing them to navigate among rocks, a narrow mouth that they use to scrape algae from rocks and a long digestive system that allows them to digest their food. They occasionally feed on shrimp and other animals and thus small portions of animal protein can be beneficial, however large amounts of such prey might cause blockage in their digestive system and lead to a disease known as Malawi Bloat.

Haps are larger species which are either sand dwellers or open water fish. The group is composed by more than 20 genera which form the majority of the Lake Malawi cichlids and include the famous genera Haplochromis, Aulonocara (peacock cichlids), Copadichromis (Utaka Cichlids). They are predators, eating smaller fish and invertebrates. They also eat smaller cichlids, thus choosing their tank mates carefully is crucial as they might feed on smaller species. They are moderately aggressive but are quite large species, requiring large tanks of at least 55 gallons (250 litres).

Soft substrate is generally more preferable for these species as rocks might constrict space for large growing haps and can cause injuries. Haps are polygamous, with male individuals forming harems of several females, thus keeping a high ratio of female to male species will encourage the formation of small schools in the aquarium. This group includes some of the most famous cichlids such as the Electric Blue cichlid (Sciaenochromis fryeri).

Both cichlid groups require warm water between 76 and 82° F (24-27° C) and an alkaline pH around 7.8-8.6. Hardness should also be maintained around 4-6 dH. Mixing species of the two cichlid groups from Lake Malawi is possible, however extreme care should be given in order to avoid extreme aggressiveness of mbunas, predation of large haps to other cichlids and cross-breeding of species.

References

Smith, M. 2000. Lake Malawi Cichlids (Complete Pet Owner’s Manuals), Barron’s Educational Series, 96 p.

Snoeks, J. (ed.), 2004. The cichlid diversity of Lake Malawi/Nyasa/Niassa: identification, distribution and taxonomy. Cichlid Press, El Paso, USA, 360p.

Duponchelle, F. & Ribbink. 2000. A fish ecology report, lake Malawi/Nyasa/Niassa. Biodiversity Conservation Project