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Experiences with Steatocranus tinanti (Poll, 1939)
|Mary Bailey, 1995.|
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Steatocranus tinanti male in the aquarium Fish and Photo by Mary Bailey.
(This article was originally published in Cichlid News Magazine; April 1992; Aquatic Promotions Vol. 1 No. 2. pp. 22-24.).
Steatocranus tinanti is a small, rheophilous cichlid from West Africa, where it is found in stretches of rapids along the Congo River in the vicinity of Kinshasa, the capital of Congo (Linke and Staeck, 1981). It has been know to science since 1939 when it was formally described as Gobiochromis tinanti by Professor Max Poll, and for a rather shorter period of time to aquarists, having not been seen in Europe until the 1980's. Like many other fishes from Congo, it was not exported for a long time due to political turbulence in that country and the quantities of wild fishes available have always been rather small. It seems to have rarely been bred it has a reputation for being difficult, though this was not my experience and has failed to achieve any degree of popularity, perhaps because of its rarity or perhaps because it lacks the stunning coloration of many of its East African cousins. This is a pity, as it is a charming and interesting little fish and usually quickly wins the hearts of those who find a place for it in their aquaria.
I have been interested in West Africans for many years and have kept several species of rapids-dwelling cichlids (Steatocranus, Teleogramma) over the past decade. When a friend phoned to ask if I would like her pair of wild-caught S. tinanti her water was not suitable, and although they had settled, there were no signs of breeding I quickly said yes, although expressing some reservations regarding their reputation for aggressive behavior, especially toward conspecifics. My friend assured me, however, that her pair were living in perfect amity and showing no inclination to murder each other or anything else for that matter.
In any event I came back from her house with not only the S. tinanti, but also a pair of Teleogramma brichardi and a couple of small unidentified Steatocranus, which it was felt would likewise benefit from my soft Devon tap water (0.5 dGH from the tap), which more closely approximates conditions in nature than the 15+ dGH in which they had been living. Luckily I had prepared a 1.20 m (48") tank for the S. tinanti, so there was plenty of space (I hoped!) for the other fishes as well.
The tank was decorated with large amounts of rockwork, mostly granite, with numerous caves of various sizes in an attempt to simulate the natural habitat. The substrate was granite gravel, of irregular grain size and containing odd pebbles, "wild caught" by myself for use in acid water tanks, as it contains absolutely no calciferous material and actually tends to acidify the water (I believe this results from the gradual breakdown of the feldspar content). The pH had stabilized at about 6.5; temperature was kept in the range 25- 26°C. Lighting was moderate, as I find that with many species of cichlids this makes for more relaxed fishes and a greater chance of breeding.
Filtration was by air-driven undergravels something which surprises most aquarists as this in no way creates the amount of turbulence these fishes must meet in their natural habitat. I had, however, learned a lot from my experiences with T. brichardi some four years previously. Then I had attempted to create turbulence by using an internal power filter with the outlet above the water surface to create a cascade effect. The fishes hated it and spent most of their time sitting under the filter canister, probably the least turbulent spot in the tank. As soon as I turned the filter off they would wander round the tank, looking far more at home in the calmer environment. If one stops to think about it, it is highly unlikely that these fishes spend all day struggling in the main stream of the rapids they aren't robust enough and probably spend most of their time in the quiet areas in the lee of large rocks. Their almost total lack of buoyancy, resulting from their greatly reduced swimbladder a feature they share with other cichlids from similar habitats, including the surf-dwelling goby cichlids from Lake Tanganyika enables them to rest quietly and effortlessly on the bottom and to flit through the narrow layer of relatively calm water along the interface between the current and the substrate. One has only to watch a rapids cichlid struggling to the surface to take flake food to realize that rising through open water is behavior quite alien to it, while its short sorties across the bottom of the tank look perfectly normal and natural.
All my fishes settled in quickly with the Steatocranus tinanti occupying a small territory together in the center of the tank, the Teleogramma separately, one at each end, and the other Steatocranus filling in what space was left. They were fed on a diet of chopped earthworms, pond foods (live and frozen), various prepared foods (beef heart, chopped mussel, etc.), and a small feed of dried food (flake or pellets) each day. The pellets were soaked first so that they would sink, as the fishes expected their food when I opened the cover, not several hours later; if I used "fresh" pellets then I had to siphon out most of them when they eventually sank.
It was quite obvious to my eye that the tinanti were a pair; the male was appreciably longer (7.5 cm., 3.0" S.L. as opposed to 5.0 cm, 2.0" for the female, and at least twice her overall bulk) with a much larger head, showing only a very small hump, which in no way approached the magnificent gibbosity of male S. casuarius. Moreover, his fins were clearly longer and more flowing. The base color of both sexes is a rather non-descript beige-brown- grey (depending on mood) with 4-5 rather broad but vaguely delineated darker vertical bars on the upper body, and two much narrower longitudinal bands, again darker than the base color. The lower of these runs from the operculum to the caudal peduncle at the mid-lateral level; the other starts just above and behind the eye and runs for much of its length midway between the caudal base and the lower band, eventually sloping down to merge with the latter below the soft part of the dorsal. These markings give a faint checkered effect overall. The vertical markings are less noticeable in females. Young specimens have a "tilapia-spot" in the soft dorsal, which disappears first in males and can sometimes still be seen in adult females.
Behavioral features confirmed the dimorphism; both fishes occupied the same cave, which they excavated slightly but not excessively, and seemed quite at home with each other, though I never saw much display. This was a great relief, as initial courtship is reported as sometimes being violent to the potential (and actual) detriment of the smaller female. I had had this problem with my original pair of T. brichardi and had to separate them with a clear divider; after a couple of months this was removed and no further hostilities occurred. Accordingly I would suggest this as a possible solution to the same problem in tinanti. It has to be said, however, that those of the offspring of this pair which were given to friends have proved no more quarrelsome than their parents.
At this time I was away a lot during the week, so feeds were not as regular as might be desired, and I did not seriously expect breeding to occur. As we all know, however, cichlids rarely operate "by the book", and I arrived home one Friday evening to find myself the proud owner of a small shoal of 30-40 tinanti fry, measuring more than 1/2" total length.
Steatrocanus tinanti female in the aquarium. Fish and Photo by Mary Bailey.
The brood care was very unusual: every morning the fry came out of the parental cave and "sat" on the top of the rock which formed its roof; the female remained in the cave except at feeding time I did wonder if she was already tending a further clutch of eggs, but no further fry appeared at this stage, so I assume this was not the case. The male spent some time resting on the roof with the fry, but also held station above them (hard work for a fish with a reduced swim-bladder). If any of the other fishes approached too closely the territory defended was about 30 cm. (12") across he would dart at it, usually scattering the fry in his wake. These, however, quickly reassembled in their "nursery". The parental behavior was unlike any other cichlid brood-care I have ever seen, with the female apparently playing no part except to help marshall the fry and take them into the cave for the night.
It was necessary to aim their food at the nursery rock, as the fry showed no inclination to leave it to forage, though upon sighting anything edible they would make small movements up from the rock to grab it. I started them on microworms rather too small, but a good wriggle factor to get them feeding - and soon weaned them onto other small foods such as cod roe and finely prepared heart.
This was the first of several broods over the next few months, with the fry gradually "leaving home" 4-6 weeks after their first appearance, by which time they measured well over 3.2 cm. (1.25"). They occupied any vacant nooks and crannies they could find and were extremely difficult to catch impossible without a certain amount of disturbance to the rockwork, and this had to be carefully timed to avoid upsetting the adults. I found the best time was when a new batch of fry had just appeared; these were taken inside at the first disturbance and kept there, and their older siblings not allowed in. I never saw the eggs it is terribly bad practice to pry and a very good way of causing egg-eating but these are said to be large and very adhesive. The fry, at their first appearance, were comparable in size to those of T. brichardi, and the eggs of that species are truly enormous. One assumes that this is an adaptation to ensure that the fry are large enough from the outset to avoid being swept away in the current.
The taxonomy of S. tinanti is rather interesting. It was originally assigned to Gobiochromis, but later relocated in Leptotilapia. Roberts and Stewart (1976) considered the latter genus to be merely part of Steatocranus, while nevertheless admitting that tinanti differs from all other members of the genus in "its very elongate body, distinctive coloration, longer caudal fin, more numerous lateral line scales, and superolateral eyes". While I can make little claim to taxonomic expertise, I am inclined to think that given these differences in appearance, and the unusual breeding behavior I have described above (which, as far as I am aware, bears no resemblance to that of other Steatocranus so far bred in captivity), it is not entirely reasonable to assign tinanti to Steatocranus simply because it has a few morphological characters in common with that genus. Over recent years scientists have started to consider behavioral features when evaluating taxonomic status, and perhaps a further revision will revive Leptotilapia or Gobiochromis for this species.
In conclusion I would heartily recommend this unusual and appealing little fish to anyone who has the chance to buy some; you will, I am sure, find them far more interesting than yet another mouth-brooder!
© Copyright 1995 Mary Bailey, all rights reserved
Bailey, Mary. (czerwca 13, 1998). "Experiences with Steatocranus tinanti (Poll, 1939)". Cichlid Room Companion. Źródło: na maja 18, 2013, od: http://www.cichlidae.com/article.php?id=95&lang=pl.