Metriaclima xanstomachus
Metriaclima xanstomachus was first described by Stauffer & Boltz in 1989. The genus name Metriaclima is derived from Greek and means “moderately inclined.” This refers to the moderately inclined head shape of the fish within this genus. The species name xanthomachus comes from Greek; xanthos means “yellow” and machē means “fight.” This could refer to the yellow throat region in males and their aggressive behavior.
Synonyms: Maylandia xanstomachus, Pseudotropheus xanstomachus.
External Characteristics, Behavior and Life Expectancy
Metriaclima xanstomachus has an elongated, laterally flattened body, typical of Mbuna cichlids. The head is usually bluish to gray in males and brownish gray in females. The flanks show variable coloration depending on the population and reproductive phase. Males often have a bluish to gray base color with dark vertical stripes. The throat area is often yellow in color. Females are generally brownish gray with less pronounced stripes. The fins may show yellow or orange accents. The maximum length of males is about 12.5 centimeters, while females remain smaller, around 9 centimeters.
!Caution: in the aquarium, they can grow much larger by being fed too much and too vigorously. The males can then grow up to about 18 centimeters in length!!!
Differences between males and females: Males are significantly larger and more colorful than females. The yellow throat region is a distinctive difference. Behaviorally, males are territorial and aggressive toward other males, while females are generally less aggressive.
Juveniles versus adults: Juveniles show a less pronounced color pattern than adults. Colors develop gradually as they age.
Behavior and temperament: Metriaclima xanstomachus is a territorial and aggressive species, both towards conspecifics and other fish species. Males fiercely defend their territory against other males. They are bottom dwellers and live mainly in the rocky areas of their habitat. The best way to keep this species is in a harem, with one male and 3-4 females.
Life expectancy: The life expectancy of Metriaclima xanstomachus in the wild is unknown. In an aquarium they can live 5 to 8 years, depending on care and conditions.
Habitat and Ecology
Metriaclima xanstomachus is endemic to Lake Malawi in Africa. Thus, the species occurs naturally only in Malawi. Within Malawi, the species is found mainly around the Maleri Islands and Kanjedza Island. They inhabit the rocky zones of the lake, often near the transition between rock and sand.
Their natural habitat consists of rocky areas with a sandy bottom. Much underwater vegetation is present in the form of algae and other organisms growing on the rocks (aufwuchs).
Lake Malawi has a tropical climate. Due to the overall size and depth of Lake Malawi, water values are very stable throughout the year.
Diet
Diet in the wild: In their natural habitat in Lake Malawi, Metriaclima xanstomachus feeds primarily on algae and other organisms growing on the rocks (aufwuchs). They scrape these food sources off the substrate with their beaks. So their diet consists of plant material, supplemented by small invertebrates found in the algae.
Diet in the aquarium: In an aquarium, their diet should consist of high-quality, plant-based foods, such as spirulina flakes, algae wafers and other plant-based tablets specifically designed for cichlids. Supplemented can be small amounts of animal foods, such as high-quality dry food, cyclops, daphnia or artemia, to cover their protein needs. It is important to provide a varied diet to ensure good health and coloration. Overfeeding should be avoided as this species tends to grow much too large!
The aquarium for Metriaclima xanstomachus
Aquarium size: A minimum of 400 liters and 150 centimeters in length is recommended for a harem (one male and 3-4 females). Multiple pairs require a considerably larger aquarium, ideally 800 liters or more, depending on the number of fish. The surface area of the bottom is more important than the height of the aquarium.
Fixtures: A rocky layout that mimics the natural habitat is essential. The aquarium should provide plenty of hiding places in the form of caves and crevices between the rocks. A sandy bottom is most suitable. Do use rounded sand for this. Plants are not important and are often not used in mbuna aquariums because they can be damaged by the fish.
Water values: Water values should approximate the natural conditions of Lake Malawi: a pH of 7.5-8.5, a total hardness (GH) of 5-15°dGH and a temperature of 22-26°C. Regular water changes are important for maintaining good water quality.
Compatibility: Metriaclima xanstomachus is an aggressive species and can only be kept with other robust and equally aggressive Malawi cichlids. Suitable co-inhabitants are other mbuna species of similar temperament. The choice of species depends greatly on the size of the aquarium and the experience of the aquarist. Choose species with different colors and markings to avoid conflicts. Keeping with less aggressive species or non-Mbuna species is strongly discouraged.
The Breeding of Metriaclima xanstomachus
The breeding of Metriaclima xanstomachus is quite easy. You can breed them in a mixed aquarium. The male is constantly looking for females to mate with. When a male gets through that a female is ready to spawn, his blue color darkens and he puts on his most beautiful colors.
He spreads his fins wide, swimming in front of the female with trembling movements. With this he wants to entice her to follow him to a place in the sand to mate. The pair circle each other just above the sand. After a while, the female lays an egg in the sand. They spin through and the female takes the egg in her maw. The male turns with her and releases some hom and fertilizes the eggs with it. This process repeats itself until the female has all the eggs in her maw. The man’s work is now finished.
For the next three weeks, the female keeps the eggs and newly hatched young in her maw and eats little to nothing. The eggs hatch after a few days but the young remain in the female’s maw for about three weeks after spawning. They feed on the egg yolk sac and continue to grow. You can tell from the female that she has a beak full of eggs by the thickening in her throat.
After three weeks of breeding, the female releases the young fish. In an aquarium with other Malawi cichlids, the young often end up as food.
If you want to breed larger numbers a rearing aquarium is needed. Set it up with some sand on the bottom and a hiding place for the female. Catch her from the main aquarium around day 17 of breeding and place her in the rearing aquarium. After the three weeks she releases the young fish. She does not eat the young fish immediately. You have plenty of time to put her back in the main aquarium.
You can feed the young fish with crushed spirulina flakes and other crushed flake food.
Conclusion
Metriaclima xanstomachus is an attractive but demanding species of fish, not suitable for beginners. Their aggressive nature and specific requirements regarding aquarium size (at least 400 liters for a harem, considerably more for multiple pairs), decoration (rocky setup with many hiding places) and water parameters make successful housing a challenge. A good understanding of their behavior and social structure is important for avoiding conflicts. The variation in color patterns between different populations is an interesting peculiarity.
Video
Author
John de Lange
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