Design and setup of an aquarium for African cichlids.
The question of the number of fish in an aquarium is directly related to an important factor: the aquarist’s ability to maintain a biological balance in the tank. Keeping African cichlids in an aquarium has a number of specific features determined by their lifestyle in nature. The waters of African rivers and lakes, where cichlids live and reproduce, are abundant in dissolved oxygen and contain very few organic compounds (waste products of living organisms and decaying vegetation). This is especially true for the Great African Lakes, where water has stable properties with an alkaline pH and crystal clarity.
To make cichlids feel as comfortable in an artificial reservoir as in their natural habitat, it is necessary to bring the properties of the water used as close to natural indicators as possible. To help aquarists, a whole range of devices capable of maintaining stable conditions such as purity, chemical composition, and a given water temperature have been invented.
To maintain water purity along with aeration, various pump filters with synthetic filter material are used. Such filters are produced in various capacities and configurations, which allows you to choose the necessary kit for any aquarium volume. To make it easier to maintain stable conditions in the aquarium, amateur aquaristics has acquired another important device: the biofilter. Biofilters, in addition to filtering water from mechanical suspension, help partially solve the issue of completing the nitrogen cycle in the aquarium—converting organic compounds into nitrates, which in reasonable quantities are not toxic to underwater inhabitants.
You should choose a system with a capacity of at least 3-5 aquarium volumes per hour. Of course, a biofilter cannot be called a panacea for the oversaturation of the aquarium with organic compounds. To maintain a set temperature in an aquarium with African cichlids, thermal regulators are used. The power of the thermal regulator is selected individually in each case and depends on several factors, the main one being the air temperature of the room where the aquarium is located.
The temperature of the water in which cichlids are kept is one of the significant factors influencing their coloration and size, offspring quality, and reproductive ability. The temperature regime of the water bodies where these fish live varies. In the Great African Lakes of Malawi, Tanganyika, and Victoria, the temperature has high stability, remaining at 26°C in Lakes Malawi and Victoria, and 25°C in Lake Tanganyika. River cichlids inhabit water with a wider temperature range of 22-30°C. Therefore, river species adapt much more easily to conditions with unstable temperatures, prolonged overheating, and water cooling. It has been noted that cichlids tolerate abnormally low temperatures much easier and recover faster than after elevated ones. Naturally, prolonged supercooling and overheating (more than 6 hours) may be fatal to the fish.
The optimal temperature for keeping African cichlids is 24-26°C. At lower temperatures, the growth of juveniles slows down first, and the period of their puberty increases. In low-temperature conditions, cichlids do not fully develop their incomparable coloration with age, and a subsequent increase in temperature does not restore the coloration. At elevated maintenance temperatures, other unpleasant processes occur. Accelerated growth and maturation lead to a shortening of the lifespan of cichlids and a rapid loss of their reproductive capacity. High temperature has another unpleasant property: it contains a very low percentage of oxygen, and therefore, with a high stocking density, a reduction in the maximum size of cichlids may occur due to their poor assimilation of food.
The presence of a sufficient amount of oxygen dissolved in water plays a special role in keeping African cichlids. The fact is that dissolved oxygen is the most fundamental factor in the growth, development, and reproduction of cichlids and is of much greater importance than other chemical parameters of water. It is the lack of oxygen that leads to the most tangible troubles in keeping cichlids: diseases, poor growth, refusal to eat and breed, and ultimately death. An aquarium with cichlids must be equipped with a powerful round-the-clock aeration system that prevents the lack of this gas in the water even in the most extreme cases. Sources of additional oxygen consumption in the aquarium are plants at night, and mollusks, microfauna, and microflora of the aquarium at other times.
In water rich in organics (food leftovers, waste products of living organisms and plants), oxygen consumption for side chemical processes can exceed reasonable limits, so it is advisable to equip an aquarium with cichlids with a biofilter and ensure proper water replacement. Regular water changes are the second guarantee of cichlids’ good mood, after aeration. The frequency of changes depends on many indicators: feeding density, aquarium volume, number of fish, and their size. The most reliable ways to determine the need for a water change are checking the smell and color of the water. Fresh water has no odor and a slightly bluish tint. Water in which many organic compounds have accumulated acquires a yellow tint and a specific unpleasant odor, signaling that the water needs to be refreshed.
All chemical and biological processes in the aquarium are directly related to the chemical composition and temperature of the water. Oxygen is a universal oxidizer of organic compounds, and carbon dioxide is the foundation for the growth of underwater flora and one of the main regulators of the water’s hydrogen exponent—pH, which is the third important component in keeping African cichlids. Practically all lake species are adapted to normal existence only in a narrow range of pH values. In the oldest of African lakes, Tanganyika, cichlids live that react sharply to a drop in the hydrogen exponent to a level below pH 7.5. Lake Malawi cichlids cannot tolerate a pH lower than 7.0.
Ignoring this factor can lead to mass mortality of cichlids in a very short time, which sometimes happens during their long-distance transportation. It should be remembered that an increase in the level of carbon dioxide in the water leads to a shift in the hydrogen exponent towards the acidic side. That is, with weak aeration, especially after feeding, a large amount of carbon dioxide enters the water through the gill covers of the fish, which can turn the water from alkaline to acidic in a short time, which will surely kill the lake cichlids. Salts that form water hardness serve as a natural buffer to restrain fluctuations in the hydrogen exponent. The higher the water hardness, the higher its buffer reserve, which provides stability of the hydrogen exponent. River African species easily withstand water acidification below 7.0, but still feel better in alkaline water.
When breeding Tanganyikan cichlid species, one sometimes has to deal with such concepts as the chemical composition of water. The water in the aquarium must be crystal clear; nothing ruins cichlids like dirt. The presence of nitrogen compounds in the water under an active alkaline water reaction leads to the formation of ammonia, which causes severe poisoning in fish. Signs of poisoning include fixed paralysis of certain body parts and various forms of scoliosis. This refers to keeping an allowable amount of organic decomposition products in the water. Special tests can be purchased at pet stores to determine the amount of nitrogen compounds in the water, the concentration of which can be critical not only for successful breeding, but sometimes even for keeping fish in an artificial reservoir.
Toxic and unacceptable compounds are primary and secondary decomposition products: ammonia, ammonium, and nitrites. The final product of organic decomposition is nitrates, for which there is a certain standard content in aquarium water. Using these tests, you can analyze the water composition for the presence of nitrogen compounds and, if they are exceeded, either improve the biofiltration system or make water changes more frequent.
Aquarium design for African cichlids. Aquarium with cichlids of Lake Victoria.
Features of keeping African cichlids in captivity. 
