Crenicichla hu

Crenicichla hu, paratypes, male (below) and female (above) (photos from publication)

Icthyologists from Argentina in conjunction with scientists from the Czech Republic have finally unveiled a new species of pike cichlid which makes its home in the Parana River drainage of Argentina.

This new cichlid was dubbed Crenicichla hu in a recently published paper in the journal Zootaxa. The lead author, Lubomir Pialek along with coauthors have distinguished this new cichlid from similar species in the area as they have a combination of dark gray or dark brown to black color body and fins, 7 to 9 black spots on their flanks, 47 to 54 scales in row E1, and the dorsal fin on the adult female species has a pattern of black and white horizontal stripes or blotches.

This new species of cichlid has formally been confirmed and recognized by a phylogenetic study which was carried out in the same paper by using the mitochondrial ND2 gene.

The cichlid was scooped up from a swiftly running, clear stream with a substrate mud, stone and sand. Its name, Crenichlia hu, comes from the Guarani word for black (hu), referring to its dark coloring.

If you would like to read more about this fascinating new cichlid, you can check out the paper by clicking the link below.
http://www.mapress.com/zootaxa/2010/f/zt02537p046.pdf

There has been an ongoing census of the fish community in Lake Tanganyika for the last twenty years. During this census the Japanese scientists have taken note of some rather drastic changes in the fish populations. These findings were published in the most recent issue of the journal “Ecology of Freshwater Fish”.

The conclusions were reached by Yuichi Takeuchi and team, while surveying the density and number of the different fish in Kasenga Point, at the southern end of Lake Tanganyika between 1988 and 2008.

The investigative team, headed by Yuichi Takeuchi, took note of a total of 54 chichlid and six non-cichlid species of fish, over the period of the survey. The most abundant type of fish recorded were the aufwuchs feeders.

Even though there was an abundance of fish and no lack of number of species present, their research indicates that there was a steep decline in the density of the aufwuchs feeders and invertebrate eaters during the course of the study. In a strange turn of events, there was an increase in the density of detritus feeders during this time.

The researches theorize that the change in the fish community could be due to human activities in the area such as deforestation, and agriculture run offs, which would lead to sediment loading in Lake Tanganyika to increase.

While they could not completely rule out natural variation for these changes in the fish community of Lake Tanganyika, there is no doubt that human activity is also making a large impact on the area as well.

In several species of fish, such as the cichlid species Neolamprologus pulcher, it is common for subordinate females to help an unrelated dominant breeding pair raise their young. The reason behind this seemingly altruistic behaviour, known as alloparental care, has puzzled scientists for many years and one of the most widely spread hypotheses put forward has been the ‘pay-to-stay’ hypothesis. According to the ‘pay-to-stay’ rationale, the subordinate female helps out the dominant pair just to be able to stay in the group. Not being ostracised from the group augments her long-term survival chances, thus increasing the chance for her to live long enough to eventually obtain a breeding position.

Picture by: JJPhoto.dk

A new study carried out by Dik Heg and coauthors does however bring forth a new hypothesis: the substrate rationale. In their study, Heg and his colleges tested the hypothesis that subordinate female cichlids are helping dominant pairs in return for a more immediate direct reproductive benefit. After a series of experiments where the total number of eggs produced over a 30 day period by dominant and subordinate Neolamprologus pulcher females were carefully counted, researchers found that a subordinate female helping out a dominant pair was more likely to produce eggs herself compared to other subordinate females.

According to Heg and coauthors, the most likely reason for the increased reproductive success of “fish nannies” is that the subordinate female gains access to the breeding substrate.

If you wish to read more, see the paper “Heg, D, E Jutzeler, JS Mitchell and IM Hamilton (2009) Helpful female subordinate cichlids are more likely to reproduce”. It has been published in the journal PLoS ONE.

Here at AC Tropical Fish, we believe in the Jude Law-hypothesis. The dominant female will naturally snatch away the most prosperous male, but by posing as a benevolent nanny even a subordinate female can gain access to his home and hope for some of his triumphant DNA to eventually find its way into the genetic make up of her own offspring.

A new cichlid species has been described from the Río Negro and Río Tacuarí basins in the Uruguay River drainage by Uruguay ichthyologists Iván González-Bergonzoni, Marcelo Loureiro and Sebastián Oviedo.

The fish has been given the name Gymnogeophagus tiraparae (picture here) after María Luisa Tirapare, a Guaraní woman who founded the town of San Borja del Yí (no longer existing) close to one of the collecting localities for this fish.

Gymnogeophagus tiraparae is found in larger rivers with clear water over both sandy and rocky bottoms where underwater vegetation is scarce. The fish is decorated with two horizontal series of moderately elongated light blue dots between the dorsal fin spines, and a series of light blue stripes between the soft rays, sometimes merging with the second series of elongated dots. Between the series of dots, the body of the fish displays a red ground colour. On this spotty fish, the caudal fin is also adorned with dots, which are vertically aligned on the distal border. The body has no transversal bands at all. Another important characteristic is how the adipose hump on the head is located deeper than the upper border of the dorsal fin.

The description was published in the most recent issue of the journal Neotropical ichthyology.

González-Bergonzoni, I, M Loureiro and S Oviedo (2009) A new species of Gymnogeophagus from the río Negro and río Tacuarí basins, Uruguay (Teleostei: Perciformes). Neotropical Ichthyology 7, pp. 19–24.

* Guaraní is a group of culturally related indigenous people of South America who speak the Guaraní language. They are chiefly found between the Paraguay River and the Uruguay River.

In a recent issue of the journal Zootaxa, researchers Gertrud Konings-Dudin, Adrianus Konings and Jay Stauffer have described and named three new species of cichlid from the genus Melanochromis; two of them being fairly widespread among aquarists keeping African cichlids.

All three species hail from the eastern shore of Lake Malawi and belong to the group commonly referred to as Mbuna cichlids among fish keepers.

The fish you may have been offered under the name Melanochromis sp. “northern blue” (picture here) has been given the full name Melanochromis kaskazini. Just like its old trade name suggests, this Malawi cichlid hails from the northern part of the lake and the word kaskazini was choosen since it is the Kiswahili word for “northern”. (Kiswahili, also known as Swahili, is an African language spoken along the continent’s eastern coast.)

The “blue” part of its old trade name is a reference to the colour of the males; they are cobalt blue, while the females are white with a yellow or orange anal fin. Melanochromis kaskazini looks quite similar to its close relative Melanochromis lepidiadaptes but the latter one sports a suit of mensural characters not seen in Melanochromis kaskazini.

The Mbuna cichlid previously sold in fish stores as Melanochromis sp. “auratus elongate” (picture here) is from now named Melanochromis mossambiquensis. The fish is named after the country Mazambique since it is found along the Mazambique shore of Lake Malawi; a lake shared between the countries Mazambique, Malawi and Tanazania.

In Melanochromis mossambiquensis, the female fish is adorned with yellow stripes on the belly and a midlateral and dorsolateral black stripe that is narrower than the submarginal black band in the dorsal fin. The yellow stripes do not cover the entire lower abdomen, and the caudal fin features black spotting. The male fish is brown/black with white dorsolateral and midlateral stripes, and he displays a suite of mensural characters.

The third Mbuna cichlid, which does not have any trade name, has been given the scientific name Melanochromis wochepa due to its small size. Wochepa means “small” in Chinyanja, also known as Chichewa, a Bantu language spoken in south-central Africa.  I have not been able to find a picture at this time.

Melanochromis wochepa males are blue without any white striping, while the females sport a submarginal dorsal band that is wider than the mid-lateral and the dorsolateral stripe, thin abdominal yellow stripes never covering the entire lower abdomen, and a suite of mensural characters. The vomer is steep-angled in both sexes.

For more information, see paper published in Zootaxa: Konings-Dudin, G, AF Konings and JR, Jr Stauffer (2009) Descriptions of three new species of Melanochromis (Teleostei: Cichlidae) and a redescription of M. vermivorus. Zootaxa 2076, pp. 37–59.

Madagascar, a large island situated in the Indian Ocean off the south-eastern coast of the African continent, is home to an astonishing array of flora and fauna. Madagascar, then part of the supercontinent Gondwana, split from Africa about 160 million years ago and became an island through the split from the Indian subcontinent 80-100 million years ago.

Madagascar is now the 4^th largest island in the world and its long isolation from neighbouring continents has resulted in an astonishingly high degree of endemic species; species that can be found nowhere else on the planet. Madagascar is home to about 5% of the world’s plant and animal species, of which more than 80% are endemic to island. You can for instance encounter Appert’s Tetraka bird (Xanthomixis apperti), the carnivorious Fossa (Cryptoprocta ferox) and over 30 different species of lemur on Madagascar. Of the 10,000 plants native to Madagascar, 90% are endemic.

The diverse flora and fauna of Madagascar is not limited to land and air; you can find an amazing array of creatures in the water as well – including a rich profusion of endemic fish species. Unfortunately, the environment on Madagascar is changing rapidly and the fish – just like most of the other creatures – risk becoming extinct in the near future.

The fishes of Madagascar currently have to deal with four major threats:

• Deforestation
• Habitat Loss
• Overfishing
• Invasive species

In a response to this, and to educe people around the world about the fish of Madagascar, aquarist Aleksei Saunders have created the website Madagascar’s Endangered Fishes on which he shares his knowledge of Madagascan fish species and the perils they’re facing, but also highlights all the things we can do to improve the situation.

The site focuses on freshwater fish conservation and captive breeding, since collection of wild fish to bring endangered species into captivity for managed reproductive efforts plays a large part of the conservation effort in Madagascar.

In addition to the website, Alex is also gives power-point presentations on husbandry and conservation breeding of Madagascar’s endemic fish fauna, since more and more aquarists around the world are taking a large interest in doing their part to help endangered fish species.

Alex has worked with fish since 1990 and it was through his work as an aquarist at Denver Zoo he became enthralled with the ichthyofauna of Madagascar. During the early 1990s Denver Zoo started a conservation program with the endemic freshwater fishes of Madagascar and in 1998 Alex got the chance to pay his first, but certainly not last, visit to the island. Today, his trips primarily focus on educating the Malagasy on their wonderful natural heritage and ways of conserving it, assessing the condition of native freshwater habitats and the fish population therein, and collecting wild fish for managed captive breeding. Alex now manages on of the most diverse collections of Madagascan endemic fishes in North America, including 5 species of rainbowfish, 4 species of cichlid, and 3 killifish species.

With this site I hope to educate, motivate, and stimulate people into action to help save Madagascar’s endangered fishes. Please look around the site. There are sections for fish hobbyists, adventure travellers, conservation biologists, and just those curious about the world in which we live.

Cheers,

Aleksei Saunders

The cichlid genus Crenicichla now has two new described members: Crenicichla tesay and Crenicichla mandelburgeri.

Crenicichla tesay

Crenicichla tesay lives in the Paraná River drainage and was described by Argentinian ichthyologists Jorge Casciotta and Adriana Almirón. The fish was caught in the Iguazú River upstream of Iguazú falls in Argentina, an environment characterized by falls and pools with clear and rapidly flowing water. The bottom in this habitat consists of stones, mud and sand.

The name Crenicichla tesay is derived from the Guaraní word for tears; the fish displays a tear-shaped suborbital stripe. You can distinguish Crenicichla tesay from its close relatives by the existence of a serrated posterior preopercle border, the number of scales on the E1 row, the length of the snout, and the colour pattern which consists of a suborbital stripe, 4–6 dark blotches and numerous irregularly scattered dots on the sides of the body.

The description has been published in the journal Revue Suisse de Zoologie[1]. For more information, see the paper: Casciotta, J and A Almirón (2008) Crenicichla tesay, a new species of cichlid (Perciformes: Labroidei) from the río Iguazú basin in Argentina. Revue Suisse de Zoologie 115, pp. 651–660.

Crenicichla mandelburgeri

Just like Crenicichla tesay, this newly described cichlid hails from the Paraná River drainage. It was described by Swedish ichthyologist Sven Kullander and named Crenicichla mandelburgeri in honour of Paraguayan ichthyologist Darío Mandelburger.

The Crenicichla mandelburgeri specimens were collected from two different environments. Some lived in the rapids of a large stream (5-10 meters wide and up to 1 meter deep) with turbid, brownish water. Others lived in a much smaller stream (up to 3 meters wide) with shallower brown water where both velocity and transparency fluctuated. In this environment, the bottom consisted of stones and sand and was generally without any plants.

Young Crenicichla mandelburgeri cichlids feature numerous narrow vertical bars along the side, which changes into an irregular dark horizontal band as the fish matures. You can also distinguish Crenicichla mandelburgeri from other crenicichlas by the distinct caudal blotch, the number of scales in the lateral row and in the E1 row, the lower jaw (which is longer than the upper), and the serrated preopercular margin.

For more information, see the paper: Kullander, SO (2009) Crenicichla mandelburgeri, a new species of cichlid fish (Teleostei: Cichlidae) from the Paraná river drainage in Paraguay. You can find it in Zootaxa 2006: 41–50.[2]

Crenicichla

Crenicichla is the cichlid genus where you can find the largest number of described species, about 75 species. They live on the South American continent where they inhabit freshwater rivers, streams, pools and lakes. The richest variation of species is encountered in the Amazon region, but you can find Crenicichla cichlids as far north as Guyana, Venezuela and Colombia and as far south as Uruguay and central Argentina where the water can become fairly cold in the winter.

Lake Victoria, the world’s second largest lake and the world’s largest tropical lake, has long been plighted by environmental problems caused by pollution and exotic species being introduced to the lake. On of the most well know of these problems was the introduction of Nile perch to the lake; a large predatory fish that all but wiped out the lakes wide variety of native, endemic species.

Moses Kabuusu, Member of Parliament for Kyamuswa country in Kalangala district, has now expressed concerns about another problem developing in the area. According to him the amount of fish in the lake has now become so low that crocodiles are increasingly looking at humans as food. The number of croc attacks on humans has indeed increased in Kalangala, but it is hard to tell whether this is due to less fish being present or if there are other reasons that have increased the number of attacks on humans.

Kabuusu warns people about spending time in the water due to the rampant problem of humans being eaten by crocodiles and adds that it is mostly people swimming in the lake and women getting water in the lake that are being hunted by crocodiles.

He has requested help by the Uganda Wild Authority.

Lake victoria beach.

This post will introduce a number of new catfish species, a couple of tetras and an a few cichlid species.

Let’s start with the cichlid species. The species known as Apistogramma sp Mamore have been scientifically described by Wolfgang Staeck and Ingo Schindler and named A. erythrura. It is a small species and the largest speciemen that have been found so far was 30.8 mm SL. (just over 1.2 inch). It seems to feed on small invertebrates. Thy can be found in waters with the following conditions pH 5.2–6.4; electrical conductivity <10–20 μS/cm; total and temporary hardness < l°dH; water temperature 25.1–31.0°C. They are cave spawners and can be bred in aquariums. The male guards a territory which can contain several females. The females guard the fry.

Scientists Felipe Ottoni and Wilson Costa from Brazil have in the latest issue of the journal Vertebrate Zoology described nine new species of Australoheros cichlids from southern Brazil[1].

Australoheros autrani, A. Barbosae, A. ipatinguensis, A. macacuensis, A. muriae, A. paraibae, A.s robustus, A. saquarema

New tetras

Two new species of flag tetra have been described[2]. Both species originates in Venezuela. The new species Hyphessobrycon paucilepis and H. tuyensis was described by Carlos García-Alzate, César Román-Valencia and Donald Taphorn in the latest issue of the journal Vertebrate Zoology. At the same time they recognize three other valid species: H. diancistrus, H. fernandezi and H. sovichthys.

Hyphessobrycon paucilepis originates from the small drainages in Lara state, northern Venezuela. H. tuyensis from the Tuy River drainage in northern Venezuela

New catfish species

Brazilian scientists Héctor Alcaraz, Weferson da Graça and Oscar Shibatta have in the latest issue of the journal Neotropical Ichthyology named a new species of bumblebee catfish from Paraguay Microglanis carlae as attribute to ichthyologist Carla Pavanelli[3]. The species is found in moderately fast flowing water in Paraguay River drainage.

Brazilian ichthyologists Luisa Sarmento-Soares and Ronaldo Martins-Pinheiro have described three new Tatia species bringing the total number of described species up to twelve[4]. The three new species described are T. caxiuanensis (named after the Floresta Nacional de Caxiuanã.), T. meesi (named after Gerloff Mees) and T. nigra (named after its dark color)

T. caxiuanensis is found in the Floresta Nacional de Caxiuanã, T. meesi in Essequibo River drainage in Guyana and T. nigra in the Uatumã and Trombetas river drainages.

Marcelo Rocha, Renildo de Oliveira and Lúcia Py-Daniel have described a new Gladioglanis catfish, Gladioglanis anacanthus, which can be found in the Aripuanã River in central Brazil[5].

Lúcia Py-Daniel and Ilana Fichberg have described a new whiptail catfish, Rineloricaria daraha. This new species is found in the Rio Daráa in the Rio Negro drainage which have given the species its name[6].

The release of sediment and algae-boosting fertilizers into Lake Victoria can cause cichlid species to interbreed in the murky water, according to Ole Seehausen, evolutionary biologist at the University of Bern in Switzerland and the Swiss Federal Institute of Aquatic Science and Technology in Kastanienbaum.

In a recent article published in Nature, Seehausen and his colleagues are shedding some light on the question of how closely related species of cichlids living adjacent to each other in Lake Victoria manages to avoid interbreeding. According to Seehausen et al, species may develop and stay distinct because of how the members of each species see colours.

Seehausen and his research team have studied closely related species of Lake Victoria cichlids where the males are either blue or red. It has since long been known that females of these species prefer to mate with the male displaying the brightest colours, but the new research suggests that both sexes have evolved to preferentially see only red or blue. This means that if a brightly coloured red male swims by a blue-seeing female, she will not be able to appreciate his sexy brightness since see can not see the colour red.

“Reds and blues live in the exact same spot,” says Seehausen,. “Colour is very important in mate choice.”

In order to fully understand the role of vision in underwater evolution, we must be aware of how light acts when it penetrates the water. Blue colours shine much brighter than red ones in the shallows, while red pigmentation trumps blue as we proceed farther down. As you probably have guessed already, red cichlid species tend to be found near the surface in Lake Victoria, while the blue ones inhabit greater depths.

To learn more about what happens to cichlids in the transition between red and blue zones in the lake, Seehausen and his team studied species inhabiting the shores of five different islands. The cloudiness of the surrounding waters varies from island to island due to variations in sedimentation, giving the researchers a great opportunity to study the effects of varying water clearness.

In comparatively clear waters, the colour that appears brighter slowly and gradually changes from red to blue with depth. This makes each species stay within its own zone and prevents interbreeding. In more clouded waters, the change from red to blue occurs much more suddenly, causing a higher prevalence of interbreeding between closely related species of fish.

Further testing in laboratory aquariums showed that hybrid females, like the ones living in cloudy waters, did not favour red males over blue ones or the other way around. This distinguished them from non-hybrid females, since females belonging to a species with red-sensing eyes picked red males in the laboratory tanks while the blue-sensing females opted for blue beaus.

Seehausen is now worried that the unchecked release of sediment and algae-promoting fertilizers into Lake Victoria will cause more and more fish to interbreed, thereby greatly reducing the number of species in a lake famous for its astonishing biological diversity and degree of endemic species. “Species diversity in this lake has imploded in the last 30 years,” Seehausen says. “It is the largest human-witnessed mass extinction of vertebrates.“

You can read more in the article “Speciation through sensory drive in cichlid fish” by Seehausen et al. http://www.nature.com/nature/journal/v455/n7213/abs/nature07285.html