(Article) Endemic Cichlids of the Nosivolo River

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Endemic Cichlids of the Nosivolo River

by Dave Schumacher

The Nosivolo River is located near the eastern coast of Madagascar near the city of Marolambo. The river holds two known endemic cichlid species: Katria katria and Oxylapia polli, as well as Paratilapia cf. polleni "Marolambo", which may be an endemic species (more on that later). Although the Nosivolo is currently in good shape, all of the cichlids here are considered to be endangered because of their highly restricted range. Should anything happen to the river, these fish are not found anywhere else. Throughout much of Madagascar, introduced Tilapia species have taken control of the lakes and rivers. Tilapia are very strong competitors, and have made a tremendous impact on the populations of many of the native cichlids. This is not the case in the Nosivolo, however. This is likely due to the swift current, which seems to be unfavorable to the introduced Tilapia.

Katria katria

Katria katria was described by Reinthal and Stiassny in 1997 as Ptychochromoides katria, and it wasn't until the end of 2006 that Stiassny and Sparks decided to give the katria it's own genus. According to Dr. Paul Loiselle, Katria katria outnumbers all other cichlids in the Nosivolo River at least 20 to 1. This is very strange, as it was the most recently discovered cichlid in the area!

With a maximum length of around six inches, Katria katria is one of the smallest Madagascan cichlids. A manageable size combined with a very peaceful disposition makes the katria an ideal aquarium fish. The body is elongated as a juvenile, but as the fish grows, the profile becomes much taller, especially near the head. Adult males develop a hump on the forehead that makes the fish look almost square shaped. Normal coloration of the fish is modest at best. Males and females both are a silvery-gray color with small black flecks on the scales. There are two black bars on the body that are wide at the dorsal and narrow to a point near the underside of the fish. When in breeding dress, males are reportedly orange in color. At this time, there are no reported spawnings of this species in the aquarium, but that is most likely because the fish hasn't been in the hobby for that long. They are being bred commercially in the ponds of a Florida fish farm, however.

Oxylapia polli

Oxylapia polli, or songatana as it is known as to the local fishermen, was described by Kiener and Mauge in 1966. As is the case with Katria, Oxylapia is a monotypic genus. Songatana occupy only the fastest flowing rapids of the Nosivolo, and have the most restricted range of the three endemic cichlids. They have a stocky, elongated body, and are mostly a dark silver with the lower portion of the body being lighter in color. They were only exported once, and breeding unfortunately never occurred. Dr. Loiselle had one specimen, and he claimed that it was the most aggressive fish he had ever kept. He tried to keep the fish in several aquariums, including a tank of larger, aggressive Malawi mbuna, and the polli began attacking them relentlessly. He finally had luck keeping it in a tank with a group of much larger Paretroplus. Oxylapia polli are not currently available in the hobby, and due to their extreme aggression, will most likely never be available in large numbers.

Paratilapia cf. polleni Marolambo

The third cichlid found in the Nosivolo River is a Paratilapia species. They are found further downstream than the other two species, where the water is calmer. At the moment, the genus Paratilapia is very confusing to hobbyists and expert scientists alike. It is still up in the air if the fish found in this region is just a locale variant of Paratilapia polleni, or an undescribed species. Males can grow over a foot in length. Females are the smaller sex. Both sexes are dark black with bright, irridescent green spots on the body. They are a pair-bonding substrate spawner. Both parents guard the spawning site.

To the hobbyist, Madagascan cichlids offer an escape from the norm in cichlid keeping. The species native to the gigantic island nation are more primitive on the evolutionary scale. Those who have taken the time to learn about and care for them are instantly hooked. Myself included!

References

Bills, Roger. 2006. "Cichlids of the Nosivolo River in Central-Eastern Madagascar." Cichlid News Magazine. vol. 15, n. 4, pp. 16-19.

Loiselle, P.V. 2006. (per conversation).

Reinthal, P.N. & M.L.J. Stiassny. 1997. "Revision of the Madagascan genus Ptychochromoides (Teleostei; Cichlidae), with description of a new species." Ichthyological Explorations of Freshwaters. 7 (3/4). pp. 353-368.

Stiassny, M.L.J. & J.S. Sparks. 2006. "Phylogeny and Taxonomic Revision of the Endemic Malagasy Genus Ptychochromis (Teleostei: Cichlidae), with the Description of Five New Species and a Diagnosis for Katria, New Genus." American Museum Novitates. n. 3535 (2006). pp. 1-55.

[JORG]

Good article Dave

I"ve been considering some madagascar's Once I have some space available