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JOURNAL OF THE AUSTRALIA NEW GUINEA FISHES ASSOCIATION

Nannoperca australis. Colourful male, recently photograhed in Ewen Ponds. R.K.

Bedotia madagascariensis. R.K.

MADAGASCAR RAINBOWFISH Christophe Mailliet & Aleksei Saunders SOLOMON ISLAND EXPLORATION Gerald R. Allen CRAYFISH RESEARCH Jason Coughtan & Shawn Leckie

MADAGASCAR RAINBOWFISH Notes on some recently discovered Bedotia species

Christophe Mailliet* & Aleksei Saunders**

Introduction

It does not take a particular talent in geography to understand that Madagascar is no closer to Sahul than Siberia is, and I agree that at first glance, this article may seem “off-topic” to the readers of this journal. However, there are interesting parallels in the fish fauna of the fourth largest island in the world and that of Australia and New Guinea, which have their origins in the time when dinosaurs still roamed the southern prehistoric continent of Gondwana. The dinosaurs are gone for sure, but rainbows still can be found on both sides of the Indian Ocean. Since the early fifties, Bedotia geayi Pellegrin, 1907 (the popular Madagascar Rainbowfish, or whatever aquarists thought to be Bedotia geayi) was probably the only member of its family, the Bedotiidae, to be present in freshwater aquaria around the world. However, in recent years, a rapidly growing number of new Bedotia species have been discovered along the East coast of Madagascar (see Mailliet & Saunders, 2004). Some of these have been scientifically described, however many are still new to science and the aquarium hobby. In March 2004, I was able to obtain specimen of two as yet undescribed species, Bedotia sp. “Ankavia” and Bedotia sp. “Lazana”, that are introduced in the following. Some information about their habitats and other aspects linked to their successful care and breeding is also given.

Habitats

According to current estimations, up to 90% of the original habitats and primary forests of Madagascar have been severely damaged or destroyed, and relatively undisturbed habitats can only be found on the steep slopes of the eastern coast and in the north-eastern part of the country. Many rivers are being dramatically affected by increased silt discharge and resulting high turbidity levels, which harm the native freshwater fauna. There are only a few “protected” areas, which are all suffering from a lack of funding and effective enforcement. Another, equally problematic threat for the endemic freshwater fauna is competition by introduced species such as Tilapia and Oreochromis spp., trout, goldfish, guppies, Gambusia, swordtails, carp, snakeheads, giant gourami, and so on. In all probability, some endemic species or local forms have already disappeared due to this catastrophic situation, and nearly all known Madagascar rainbowfish are considered to be endangered or even critically endangered. The same is true for a number of endemic cichlids and other species, such as the killifish of the genus Pachypanchax. Some forecasts say that within 20 years, the vast majority of the endemic freshwater fauna will have disappeared for good – a gloomy, but realistic scenario.

Bedotia and Rheocles spp. (Bedotia’s sister genus) can be found in several freshwater habitats of the eastern coast of Madagascar, and two species have also been found in very slightly brackish habitats. Most of the species are apparently found in soft, acidic waters, however detailed information is often lacking. Aleksei Saunders (Denver Zoo) was able to record quite similar water conditions in a number of habitats: pH between 5.0 and 6.5, dKH under 1, dGH under 1, and temperatures between 21 and 26°C. Bedotia are generally found in the fast-flowing upper reaches of waterways and up to altitudes of around 800 m, while Rheocles were found in habitats ranging from mountain rapids to larger lakes. …

*IRG and ANGFA Member, Berlin, Christophe.Mailliet@web.de **Denver Zoo, alekseisaunders@comcast.net

... Madagascar Rainbowfish

Biogeography and systematics

It is generally accepted that Madagascar’s separation from mainland Africa occurred 160 Mio years ago, when the “supercontinent” Pangea split and today’s continents started drifting towards their present location. Madagascar was longer connected to the southern prehistoric continent Gondwana (comprising Antarctica, South America, Australia and India, with which it was probably connected up until around 80 Mio years ago) than to Africa, to which it belongs today in the geological sense (Hay et al., 1999). It possesses a highly endemic and unique fauna and flora, which is due to millions of years of undisturbed evolution. In recent years, a number of phylogenetically primitive cichlids as well as numerous species of bedotiid rainbowfish were discovered, disproving assumptions that Madagascar had a depauperate freshwater fauna, and underlining the need to preserve Madagascar’s biodiversity.

Newer research has shown that, bedotiids may be more closely related to melanotaeniids than previously thought, and the currently prevailing opinion is that the Bedotiidae should not be treated as a separate family anymore, but rather as part of a subgroup (tribus) within the sub-family Melanotaeniinae (family Melanotaeniidae). That subgroup would include Bedotia and Rheocles of Madagascar as well as Rhadinocentrus and Cairnsichthys of Eastern Australia. Another subgroup would include the Australian and New-Guinean genera Melanotaenia, Glossolepis, Chilatherina and Pelangia. The second subfamily of the Melanotaeniidae would be the Iriatheriniinae, with Iriatherina werneri Meinken, 1974 as only member (Aarn & Ivantsoff, 1997). Recently, the creation of a new subdorder Melanotaenioidei in Atheriniformes has been proposed, which would comprise the Bedotiidae, Melanotaeniidae, and Pseudomugilidae (which in this case would include the Telmatherinidae, or Sulawesi rainbowfish) (Sparks & Smith, 2004). Just how close these families are related is still unclear, but the consensus is that, indeed they are very closely related. This of course shakes several assumptions about the break-up of the Gondwanan landmasses, but evidence seems to be mounting that Sahul and Antarctica, India, and Madagascar could have been in fact connected until the late Cretaceous period, i.e. around 80–90 million years ago. This in turn would mean that the common ancestor of today’s melanotaenioid fishes would have to be much older than today’s known fossils of atherinids, if indeed their current distribution can best be explained by vicariance events linked to the gondwanan break-up.

There have been reports of (infertile) crosses between Bedotia and Melanotaenia, however I could not find any documented evidence for this information. Although I could observe cross-genera mating activities when kept in the same aquarium (e.g. between Melanotaenia pierrucciae and Bedotia sp. “Ankavia”), I have never seen any Bedotia species spawn with Melanotaenia or any other rainbowfish. Maybe it would be worthwhile to test this assumption in a controlled breeding experiment – even just to satisfy the Frankenstein in me! In this context, it is very interesting to note that the males of some of the undescribed Bedotia species show a nape-flash when mating, just as many Australian and New-Guinean rainbows do. This anatomical peculiarity seems to be another indication that, indeed Bedotiids and Melanotaeniids are very closely related, beyond mere coincidences due to possible evolutionary convergence.

Care and reproduction of Bedotia species in captivity

Bedotia species can be kept in nearly every spacious tank, and the known species reach total lengths between 8 and 15 cm. Stomach content analysis of wild-caught specimen reveal a diet mostly based on terrestrial insects, which is why they quickly disappear when the forest canopy of their habitats is destroyed. Just as with their Sahulian counterparts, regular water changes (25% per week) are mandatory to keep them healthy. They are very active, schooling fish, and need lots of swimming space, as well as hiding places and vegeta-tion cover for females that are unwilling to spawn or dominated males. Mating and spawning procedures are similar to those of the Melanotaeniidae in some aspects: After intensive

courtship, in which the males present their erected fins and best colours, the male will place itself very close to the female above the chosen spawning site, and the pair, now side by side, propels the eggs and sperms into the substrate, on which they hang by adhesive threads. Sometimes, the males would give a lateral “nod” of the head just before spawning. Apparently, in nature Bedotia would spawn on rocks and roots as their habitats are often devoid of aquatic vegetation. Depending on temperature, eggs will hatch in around 10 days, and the newly hatched fry are capable of ingesting small Artemia. However, feeding infusorians is

safer and guarantees that the larvae get enough food in the early stages of their life. Of course they can also be raised on commercial foods, but this seems to affect growth and coloration negatively. When the parents are well-fed, they do not seem to bother too much about their eggs and offspring, but it is better to separate them to avoid any cannibalistic temptations. Growth rates are by far not as slow as with Sahulian rainbows, and young Bedotia start showing their colours relatively soon. …

... Madagascar Rainbowfish

When keeping Bedotia sp. “Lazana” and Bedotia sp. “Ankavia” in the same tank, I could observe cross-species mating activities, leading to the assumption that unintended crosses are indeed possible. Thus, fry from a Bedotia community tank should not be raised or distributed, to prevent any problems with the purity of the strains.

Bedotia sp. “Lazana”

Bedotia sp. “Lazana” is a species that has already been dis-covered some years ago, and it has been collected repeatedly in the Lazana River and its tributar-ies in the vicinity of the town of Beforona. This town is located in central Eastern Madagacascar, on the road leading from Antananarivo (the capital) to the coast. It inhabits fast-flowing sec-tions of that river, and its status in the wild seems to be relatively secure, although it shares its habitats with introduced sword-tails that apparently are now the most abundant species in that stream.

This fish has been nicknamed the White-Fin Rainbowfish in the hobby, and it is indeed a fitting denomination. Basic colour is a light grey, with bluish-turquoise reflections (particularly in males). But perhaps the most distin-guishing feature is the presence of numerous small black spots and speckles on the flanks of adult fish, and to some extent also on the fins. Every fish has its own distinctive pattern. Additionally, particularly males have enlarged fins with a pecu-liar, nearly trapezoid shape, and their unpaired fins are edged in pure white – hence their popular name. Males can reach up to 9 cm total length, whereas females reach about 7 cm. They are very easy to satisfy, and will accept any food, although they have a marked preference for live foods such as mosquito larvae or daphnia. However, they will not pick up food that has fallen on the bottom of the tank or on plants, so it is important to add some bottom-dwelling fish as tank mates, who will ensure that no food is left to decay in the tank.

Breeding them has proven to be a somewhat challenging under-taking. Males in breeding mood can be quite aggressive, and it is important for the health of the females that there are places for them to hide when the males become too pressing. I usually set them up for spawning in a 1/3 ratio, also because they are not very productive in terms of egg numbers. At best, after one week, I would obtain around 30–40 larvae, and the larvae seem to be very delicate during the first days, resulting in losses of around 50% within the first weeks. Interestingly, adult fish seem to ignore their eggs and larvae, and I have found freshly hatched young swimming happi-ly among the adults. The larvae are not very surface-oriented and roam all regions of the tank in search of food. Usually the fish reach 3 cm within 3 to 4 months. At around 6 months of age, they become sexually mature and sexing them is not very difficult, as even young males are significantly larger than young females, and more vividly coloured.

Several species of Bedotia are currently being examined at the American Museum of Natural History in New York, and pre-liminary studies have already indicated that this species is …

... Madagascar Rainbowfish

Bedotia madagascariensis. C.M.

a valid one, although formal description is still pending. But it is a very odd-looking fish when compared to other Bedotia, particularly to B. madagascariensis, of which it is supposed to be a sister species based on recent genetic analysis. Maybe addi-tional, detailed morphological analysis will reveal more about their status in the future, as in my eyes their general appearance is closer to that of Rheocles derhami and R. vatosoa, which have recently been placed in a third bedotiid genus, “Rheocles”, by Sparks & Smith (2004), than to most other Bedotia species. However, this third genus still has to be formally described, and there is still a lot of work to accomplish to better understand the intrafamiliar relationships of bedotiid rain-bows. A group of Bedotia sp. “Lazana” makes for a fantastic display. Depending on the light that falls into the tank, their colours sparkle in a myriad of bluish to green, and even golden tones, and mature males are constantly displaying to each other their flag-like fins. They are decidedly peaceful towards their own kind and other fish, and I am currently keeping them in a tank together with the nice orange variant of Chilatherina fasciata found in Lake Nenggwambu, the type locality for

Glossolepis dorityi, without any problems.

Bedotia sp. “Ankavia”

Bedotia sp. “Ankavia” has been discov-ered in the late nineties by Dr. Paul Loiselle (USA), who successfully import-ed it in the USA where it was bred and distributed in the aquarium hobby by the well-known aquarist Rosario LaCorte. The known range of this species is in the Ankavia river, which flows in the north-eastern Antalaha province and reaches the Indian Ocean near the city of the same name. Not much more is known about its habitats, however a very simi-lar – if not identical – species occurs in the adjacent Ankavanana drainage, where they inhabit smaller tributaries of the main stream. Bedotia sp. “Ankavia” is probably relatively closely related to Bedotia masoala Sparks, 2001, which occurs in tributaries of the Onive River, some 50 km further south of the Ankavia and Ankavanana. B. masoala shows a metallic, more greenish body colour with numerous black speckles, yellowish unpaired fins, and a caudal edged in red. Unfortunately, this appar-ently beautiful species has never been exported for the hobby, and it is unlikely that this will ever happen, as most of their known range lies within the Masoala National Park. Bedotia sp. “Ankavia” has also been provisionally recognised as a valid species, and will hopefully soon be formally described.

Males of Bedotia sp. “Ankavia” reach approximately 11 cm total length, with females generally being much smaller. Males have a faint blackish midlateral stripe which is more apparent towards the caudal, and shiny, dark bluish to turquoise reflective scales on their sides. When the fish become excited, their colours intensify greatly and a black reticulation, sometimes fusing to very tiny black speckles, is apparent over most of the body. Their back is a dark orange-brown, and their otherwise clear unpaired fins have a reddish-maroon edge and are moderately pointed. The caudal fin of the males is slightly forked and shows a broad red band at the posterior end. Golden to reddish reflexive scales along the midlateral stripe add a further touch of colour to this beautiful fish. Females have a broad, dark mid-lateral band, and a blackish stripe on the belly at the basis of the anal fin, sometimes giving the appearance of a double stripe. Mature males are very often displaying to each other, which is a magnificent sight, with their colours flashing in metallic shades of blue and green. The metallic sheen gets more and more intensive as the fish mature, and young males have only few metallic scales on the posterior half of their bodies. Interestingly, some males do not have pointed, but rounded

... Madagascar Rainbowfish

unpaired fins, and it seems possible that only dominant males develop such extended finnage. Among my first offspring of this species, I even have a specimen that is apparently hermaph-roditic, in that it has the coloration and habits of a female, but the physical robustness and sometimes the behaviour of a male. It would compete with other males and try to mate with females, however I have not seen it spawn yet. Maybe it is just a very odd specimen, however it would be interesting to have a detailed look at this fish once it has departed my tanks.

Maintenance is very similar to what has been said about Bedotia sp. “Lazana”. Given sufficient swimming space, the Ankavia rainbows are generally peaceful, however sometimes males in breeding mood tend to show some aggression towards competing tankmates. Breeding them is easy, and so far they have been much more productive than Bedotia sp. “Lazana”. A trio set up for a week generally produces good numbers of fry, and meanwhile offspring of this species has been distributed to several hobbyists in Germany and Belgium, where they are called the Turquoise Rainbow. Growth is relatively quick, and within 4 months, young males show first hints of their final coloration. All in all, this is a fish that has great potential for the aquarium hobby.

Outlook

This presentation of two of the newly discovered Madagascar rainbows is just a small sample of what this island has to offer to the rainbowfish afficionado. On these pages, some other recently discovered species are also pictured, which are currently being kept at the Denver Zoo in the USA in the framework of a captive breeding programme, as an attempt to keep viable populations in captivity. Even though some doubt that such efforts can effectively contribute to the survival of endangered species, I believe it is our duty to at least try to alleviate some of the damage already done. Some of these fish have been made available for the aquarium hobby in the USA, and now also in Europe, while others have yet to be released. I believe these fish are just as magnificent and worthy of our attention as their relatives from the eastern side of the Indian Ocean, and I hope that my enthusiasm for them is contagious and has kindled your interest!

Selected Literature

Aarn & W. Ivantsoff. 1997. Descriptive anatomy of Cairnsichthys rhombosomoides and Iriatherina

werneri (Teleostei: Atheriniformes), and a phylogenetic analysis of Melanotaeniidae. Ichthyological.

Explorations of Freshwaters 8(2): 107–150. DiBlasi, C. 2001. Bedotia – Freshwater Fishes of Madagascar. In: 13th Annual Symposium of Final

Presentations – Research Experience for Undergraduates: 7. American Museum of Natural History.

(see also: http://research.amnh.org/grants/REUHTML01/catherine/sld001.htm). Hay, W.W., R. DeConto, C.N. Wold, K.M. Wilson, S. Voigt, M. Schulz, A. Wold-Rossby, W.-

C. Dullo, A.B. Ronov, A.N. Balukhovsky, and E. Soeding. 1999. Alternative Global Cretaceous Paleogeography.In: The Evolution of Cretaceous Ocean/Climate Systems. (Eds. Barrera, E. and Johnson, C.): 1–47. Geological Society of America Special Paper: 332.

Mailliet, C. & Saunders, A. 2004. Review of recent work on Bedotia spp. (Teleostei: Atheriniformes)

both described and recently collected. Aqua – Journal of Ichthyology and Aquatic Biology 9(2):

45–64. Sparks, J.S. & W.L. Smith. 2004. Phylogeny and biogeography of the Malagasy and Australasian rain-

bowfishes (Teleostei: Melanotaenioidei): Gondwanan vicariance and evolution in freshwater. Molecular

Phylogenetics and Evolution 33(3): 719–734.

Sparks, J.S. & M.L.J. Stiassny. 2003. The freshwater fishes of Madagascar: Introduction to the Freshwater Fishes. In: The Natural History of Madagascar. (Eds. S. M. Goodman and J. P. Benstead): 849–863. Chicago University Press.

 

You can download this article in pdf format here (you will need Adobe Acrobat). This article is presented under permission from the Author.

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