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Keeping and breeding Ectodus descampsii Boulenger, 1898
作者 Thomas Andersen, 2006.
A revised and expanded second edition covering all basics for successfully keeping Tanganyikan cichlids
|A beautiful Ectodus descampsii male at Kalambo, lake Tanganyika Photo by Ad Konings. Determiner Ad Konings.|
For an overview of the current taxonomical status in the genus Ectodus, please see Synopsis of Ectodus Boulenger, 1898 and Ectodus species reversed. In short, what was previously believed to be an undescribed Ectodus species known under the working name of E. sp. "descampsii ndole" (Konings 1998), is with all probability the Ectodus Boulenger described in 1898, and the species previously believed to be the real Ectodus descampsii an undescribed species, E. sp. "north". A species that currently are under description (Verne 2001; Jos Snoeks, pers. com.).
Ectodus descampsii has many similarities, both morphological and behavioral, in common with a group of sand-dwelling cichlids consisting of Lestradea perspicax, L. stappersii, Cardiopharynx schoutedeni and of course the above mentioned undescribed Ectodus sp. "north". They are all silvery colored and very elongate fishes, perfectly adapted to a life over the vast sandfloors where refugees are few, and they are often seen school together in the Lake (Eysel 1990).
Molecular phylogenies have shown that Ectodus are closer related to the so called "featherfins" (species in the genera Ophthalmotilapia, Cyathopharynx, Cunningtonia and Aulonocranus), than to Xenotilapia and Callochromis, and that Ectodus together with Lestradea, Cunningtonia and Aulonocranus form a subclade within the Ophthalmotilapia-clade (Koblmüller et al. 2004).
Ectodus descampsii female in the aquarium – males as well as females have a black spot in the dorsal fin, but the spot is smaller and not so distinct in females Photo by Thomas Andersen. Determiner Thomas Andersen.
The body of Ectodus descampsii is elongated with a power caudal fin; it obtain a total length of 14 cm for the males, while females stay a little shorter. Juveniles and adolescents of both sexes, as well as subdominant adult males, are identical colored and it can be very difficult to distinguish between them. Dominate males are generally stockier build with a higher body and dorsal fin, giving the latter an almost flag-like appearance. Both sexes have the black spot surrounded with a blue halo in the dorsal fin, but the spot are much bigger and distinct in sexually active males, which are also adorned with beautiful yellow unpaired and ventral fins.
The distributional range of Ectodus descampsii encompasses the shorelines of Zambia, as well as the southern part of Tanzania.
Ectodus descampsii is a true sand-dweller, and the silvery body is a perfect adaptation to the life over the vast sand-floor where refuges are few; the silvery body reflects the sandy bottom, so it blend well with the light background and makes it difficult for predators to make it out. If a danger suddenly appears, E. descampsii will trust itself into the sand, completely hiding the body for several minutes. This behavior can also be observed under aquarium conditions and makes them quite difficult to catch. I clearly remember the first time I had to move some rocks in an aquarium containing E. descampsii – when my hands hit the water all fish disappeared with an amazing speed and were gone within a second.
Ectodus descampsii are usually found in large schools in shallow water, foraging from the bottom. It feeds on anything it can find in the sand, which is filtered and chewed, but their main diet consists of insect larvae and small crustaceans. It is a maternal mouth-brooder and in the lake males construct large sand-scrape nests in order to attract the attention of females (Konings 1998).
Ectodus descampsii males acquire a black coloration during spawning; the color is under control of the nervous system and may appear and disappear in a couple of seconds, and is brought about by melanocytes that carry the pigment. The water movement in the shallows will produce a constant mist of fine sand-grains that will blur out much of the outlines of the fish living there, and the black coloration makes the males more visible for females in the misty water (Konings 1988).
I have often heard stated that Ectodus descampsii is a relatively calm and non-aggressive species; my experiences with them has learned me otherwise. Males can be very aggressive towards each other and non-ripe females, as well as other tank inhabitants. Keeping this in mind and the fact that they like to swim a lot, the tank should not be too small. A single male seldom shows his true colors, so it is better to keep at least two males with a group of females – such a group demand a tank with a length of 130 cm (app. 4.3 feet); three males a tank with a length of 150 cm (app. 5 feet) or more, if you want to keep other fishes as well. I’ve had three full grown males displaying at the same time in such a tank – a really, really beautiful sight.
The bottom of the tank should consist of a layer of fine sand and some rocks should be added to provide the males with some territorial markers. To offer mouth-brooding females some shelter, groups of Vallisneria could be added as well. E. descampsii should be fed a diet consisting of frozen artemia, cyclops and black mosquito larvae and some quality flake food. They like to pick on algae as well, so flakes with a vegetable content are preferred.
As mentioned earlier, Ectodus descampsii is a maternal mouth-brooder where territorial males build large sand-scrape nests in order to lure ripe females to spawn. This is also the case in captivity; the biggest nest I have seen measured well over 40 cm (app. 16 inches) in diameter and were app. 10 cm (app. 4 inches) high.
|In lake Tanganyika the males of Ectodus descampsii build big sand scrape nests; a male in his nest at Namansi is here shown……… Photo by Ad Konings. Determiner Ad Konings.|
|……and the males do the same in the aquarium – a wonderful sight! Photo by Thomas Andersen. Determiner Thomas Andersen.|
When displaying the males get completely black pelvic fins and throats and tries to lure every passing female down to the his nest, while every other intruder are aggressively chased away. If a male succeeds, the female will quickly lay some eggs which are immediately fertilized by the male before being taken in by the female. This sequence is being repeated until the female is empty of eggs. In more than one occasion, I have witnessed a subdominant male colored like a female, sneak up on the spawning couple, and actually succeed in releasing his semen over the eggs. When the dominate male discover what’s going on, he will very aggressively chase the other male away – the whole scenario only lasts for a couple of seconds, but is an amazing sight.
|Mouth-brooding Ectodus descampsii female in the aquarium Photo by Thomas Andersen. Determiner Thomas Andersen.|
Clutch size varies normally between 15 and 40 eggs which are brooded for about three weeks, before the female release them for the first and last time. As soon as the fry has been released they form a tight school. Spawning always takes place late in the evening or early in the morning, and I noticed that direct sunlight or sunlight in the room in the morning, heavily increases spawning activities.
I have also noticed some quite peculiar with two of my males. When the light in the tank were turned off and the only light coming in was through the windows, one of my males always displayed – the moment I turned the light on, the males color faded within seconds and another male took over displaying in the same nest! If I turned the light off again they would shift again within seconds, and so the game could continue seemingly forever!
Ectodus descampsii is a stunningly beautiful fish, with a very interesting behavior that never cease to amaze me. Just remember that they need plenty of space for their nest building and displaying, and choose their tank mates with care, as it can be one of the more rough sand-dwellers, that easily can stressed some of the more calmer Xenotilapia species.
© Copyright 2006 Thomas Andersen, all rights reserved
Andersen, Thomas. (一月 14, 2006). "Keeping and breeding Ectodus descampsii Boulenger, 1898". 慈鯛魚室同好網. 檢索 五月 24, 2013, 來自: http://www.cichlidae.com/section.php?id=115&lang=zh.