Two New Paretroplus species

(This article was originally published in Cichlids Yearbook Vol. 6 pp. 46-47, It is reproduced here with the permission of author Jean Claude Nourissat and Cichlid Press).

Following our arrival on the east coast of Madagascar and our encounter with Ptychochromis, the second cichlid that we found was Paretroplus polyactis, which is still very common in the Pangalanes canal. This species grows fairly large: a length of 25 cm is possible, and Catala (1977) states that it is possible to find specimens weighing 750 or even 900 gm. Its vernacular name, phoneticised (it is spelt differently in Malagasy), is "Machvouatok".

The Pangalanes canal runs for hundreds of kilometres from north to south along the Indian Ocean coast of Madagascar, and contains brackish water, as in many places it is connected to the ocean, allowing salt water to enter the system. Both Ptychochromis and Paretroplus adapt very well to brackish water. I made numerous dives in the Ambilalelaitso area and a little further away in the Ampanotoamaizina region, but failed to find a breeding pair, despite searching extensively, both in the Pangalanes canal itself and the adjacent marshes where the water is extremely soft. I wanted to find some juveniles, which would be easier to transport home than adults. Perhaps it was the wrong time of year (I was there in January).

Paretroplus polyactis is fairly well coloured in this part of Madagascar; it would appear that further north, in the Maroantsetra region, they are much redder. They are rather timid fishes that show little inclination to approach a diver even if, like me, he remains motionless on the bottom. In the clear waters of the Pangalenes canal one can see them patrolling in small bands of 5 or 6 individuals, foraging in the substrate. They are bottom-sifters which pick up a mouthful of sand, extract anything edible, and then eject all the sand via their gills. This species is the most highly prized of all Malagasy fishes as regards culinary value. Its flesh is like that of a sole, pink (rather like the colour of salmon), and quite delicious, and everyone who had had the chance to taste it told us that this was a truly extraordinary fish. I haven't tried it myself, not having caught it in sufficiently large numbers.

Catala (1977) has studied this species, and shared his observations with us, commenting that he had never managed to get this fish to breed in the artificial lake near his home; although he had frequently seen them breeding in the rivers they had always refused point blank to reproduce in semi-captivity. I have no experience of keeping and breeding them in the aquarium, having failed to keep alive the 3 or 4 individuals which survived the journey home.

When planning our researches into the other cichlids of the genus Paretroplus, the only reference work available was Kiener & Mauge (1966), which we absorbed to the full. The authors provide maps of the geographical localities for the various Malagasy cichlids, and 4 species of Paretroplus are said to inhabit the northwest region. Local conditions have, however, changed considerably since they were there, (The tilapia invasion has changed everything) but it was this area that we needed to visit in order to try and rediscover the native cichlids. We were completely independent, thanks to the 4wheel-drive we had rented in Tananarive, and we visited all the rivers and lakes along the road which runs as far as Majunga, a distance of a little over 500 km. Crocodiles are common all over the island, and there is no question of diving willy-nilly without first consulting the local people. In order to minimise the danger our preferred method of fishing was with a cast net.

A Paretroplus maculatus in the home aquarium. Photo by Jean Claude Nourissat.

But time and again, all along the route from Tananarive to Majunga, we found numerous lakes and marshes where we caught nothing but tilapias. It is quite incredible how these fishes have invaded everything; lakes, rivers, and streams. Their young grow faster than those of the native Malagasy cichlids and they have completely overwhelmed the latter to the point where they have completely disappeared from the majority of lakes where they were formerly very numerous.

A large nature reserve has been established in the forest of Ankarafantsika, near to the town of Tsaramantroso. We stopped at the forestry station and were able to visit a small lake, with reasonably clear water, close to the road. Fishing is forbidden there except with rod and line, but we were able to get special permission to use our cast net, and were lucky enough to catch two new Cichlids which we had never met before: Paretroplus maculatus and P. kieneri. We had to catch more than 100 tilapias to get one Paretroplus, but we persisted, and were rewarded with several of the latter.

The first year we visited this lake the largest specimens we caught measured no more than 10 cm. They had the large black mid-lateral spot characteristic of the genus, and were easy to transport as there was no problem with lack of oxy gen due to overpopulation of the container!

We had already seen a few specimens in the market at Tananarive. All the fishes caught for food in Madagascar are dried in the sun or over wood-fires, making it possible to transport them to the point of sale. There is no electricity in the countryside or the villages, only in the towns, and there are no refrigerators and even less refrigerated transport. By making a few enquiries in the market we learned that these Paretrophts maculatus came from the Maevatanana region, where they still inhabit the lakes in the area, which, however, we had not fished.

The next year, during our second trip, we caught numerous large Paretroplus in the lake near Tsaramandroso. It must have been the breeding season (it was October), as on several occasions we caught two large adults together in the cast net, and they were exhibiting the black throat which appears to be their nuptial coloration. Because of the crocodiles, very much in evidence in this lake and which had attacked someone not long before, it goes without saying that our diving masks remained in the car. We were unable to catch any juveniles, but as I write there are some 8-10 Paretroplus maculatus swimming around in my aquarium, although I have not so far managed to breed them. I have seen ovipositors protruding on several occasions, but without any further developments.

Finally, a note on coloration. There is considerable variation in the colour pattern of these fishes: sub-adults commonly exhibit dark vertical bars, but these seem to disappear completely in large specimens. The lyre-shaped tail, bordered with red, is very similar to that of P. petiti and P. menrambo. A beautiful and elegantly shaped fish, whose colours are, however, rather unassuming.

References

• Catala, R., 1977, " Poissons d'eau douce de Madagascar", Rev. fr. Aqu ariol. l; pp 27-32.
• Kiener, A & M. Mauu, 1966. "Contribution a 1'etude systematique et ecologique des poissons Cichlidae endemiques de Madagascar.", Meet. Mus. Nntl. Hist. Nat. 40(2); pp 51-99.