THE AFRICAN EARTHEATER
We usually think of eartheaters as South American. Michel Keijman introduces a rarity from Africa that has evolved its own sand sifting strategy.
MANY AQUARISTS will already be aware of the South and Central American eartheaters, cichlids of Amphilophus and Geophagus. But did you know that there are also African eartheaters? These not only behave like their American counterparts, sifting through sand for edible particles before spitting it out again, but they also bear a striking resemblance to the fishes of Geophagus.
Meet the African eartheaters of Tylochromis. Alas, these are hardly known within the hobby, in part due to their scant availability, but also because of the bland and silvery plumage of the juveniles. This latter point is a shame, as the adults carry stunning colours, but you need to be patient — the true markings don’t become apparent until the fish reach around 20cm.
Worse still, that can easily take two or three years to achieve — Tylochromis are slow growers!
Tylochromis history
Until the beginning of the 20th century only a few of these fish were described, originally placed in the genera of Paratilapia/Pelmatochromis. It was not until 1920 that the ichthyologist Charles Tate Regan placed several species into an independent genus, Tylochromis.
For a long time, neither the hobby nor science paid any attention to Tylochromis. This changed in 1990 when ichthyologist Melanie Stiassny took up the genus and revised it, at the same time describing nine new species. This brought the genus up to 18 valid species, but there will almost certainly be more — since the time of the revision, a number of new species have been discovered in the Congo. However, since 1990 nothing has changed in the status of the species or in the genus Tylochromis. This has to do with the poor availability of species in general, but also with the lack of interest in this genus among ichthyologists.
The described species as they currently stand are: T. microdon; T. aristoma; T. pulcher; T. leonensis ; T. intermedius; T. jentinki; T. sudanensis; T. trewavasae; T. praecox; T. robertsi; T. elongatus; T. lateralis; T. labrodon; T. mylodon; T. regain; T. variabilis; T. bangwelensis; and T. polylepis.
Distribution and habitat
All representatives of the genus Tylochromis occur in Africa. But Africa is a big place and Tylochromis also has a relatively large distribution area which is ‘limited’ to the sub-Saharan part of this continent, south of the Sahara. An interesting point is that although the genus occurs in the middle Niger system and Benue system, it is absent from all systems of the Nile and Sudan. This includes a presence in the upper reaches of the Kasai system and the Shaba region, while there is an absence in the entire Zambezi system.
Stiassny notes that the range of Tylochromis almost mirrors that of the Hemichromine and Pelmatochromine fishes. The habitat of Tylochromis is chiefly characterised by main rivers and the open water parts of large lakes (even in brackish water lagoons), though some species
We usually picture South American cichlids as the only ones that sift through substrates. Michel Keijman introduces a rare fish from Africa that has its own ‘earth eating’ strategy.
can also be found in smaller rivers where they tend to live near rapids. In my opinion, the genus can be divided into two groups: lakedwelling lacustrine species and river-dwelling fluvial species.
Examples of lacustrine species are T. polylepis and T. bangwelensis, while examples of fluviatile species include T. lateralis, T. sudanensis and T. trewavasae.
What all species have in common, however, is that they like to live in biotopes where the bottom consists of a predominantly sandy substance.
This ties in with their feeding method — sifting through sand and fine gravel in search of morsels. Tylochromis are ‘benthic bound’ fishes, which means that they are always restricted to the living over and closely to the substrates of wherever they are found.
Stomach studies have shown that their food items consist mainly of organic and inorganic substrate particles, large and small invertebrates such as molluscs, crustaceans and worms, insects and even snails. There are even some species adapted to eating snails, and research into pharyngeal (throat) teeth has revealed teeth that are extremely thickened — perfect for crushing tough shells.
Males and females
It is difficult to describe the build of Tylochromis in general, as some deviate from any general pattern. But as a loose rule, one can say that they are mostly deep-bodied fish. The forehead runs convexly upwards and the males are larger than females in all known species.
Males and females can be distinguished from each other even when they aren’t spawning. Males grow larger, depending on the species, ranging from 20cm to as much as 45cm.
As males mature, they begin to develop a dotted/spotted pattern on the head, depending on the species. Another distinctive feature is also only present in males, namely a stripe pattern that can look totally different between species. Furthermore, males show colour in the dorsal fin.
Females on the other hand show a mostly silvery basic colour, and
almost always present some red at the lower end of the tail fin. But the most striking feature is the presence of a red spot at the tip of the mouth. The female often only shows this patch when she is ready to mate — this red mark has a clear function during the breeding season.
Specifically, the spot acts as an indicator of a safe haven for fry. When Tylochromis young are spooked they head for this clearly visible red spot, and thus into the mouth in and away from danger.
This characteristic is completely absent in males. But while females are generally dull in colour, the males can more than make up for that.
Tylochromis lateralis
Of the very few specimens available in the aquarium trade, T. lateralis is the only species which appears at all, and only once every few years. Even then it usually arrives as by-catch, as it isn’t explicitly sought out by collectors, mainly due to the fact that Tylochromis look like ‘silver herrings’ up to the adult stage.
This didn’t discourage me when, to my surprise, I unexpectedly found three specimens for sale in an aquarium shop. I immediately bought three of the silver fish and took them home and put them in a 250cm aquarium where I hoped they could quickly grow on.
Because of its scarcity, I quickly discovered a lack of information available. I started looking for first descriptions of Tylochromis species in general and then of lateralis in particular — I ran into a wall and could not find anything. The species is mentioned in scientific literature about fish from the Congo, and then specifically about where it occurs, but that’s it.
The distribution area of Tylochromis lateralis is usually mentioned as the middle course of the Congo River, but it is also found in tributaries such as the Kasai, Duwa, Lulua, Sankuru, Sangha, Tshuapa and Itumbiri. In these rivers, it mainly inhabits those parts of the rivers where the soil is sandy, of course because of its eartheating behaviour.
It turns out that this is something it eagerly continues to do in the aquarium.
Aquarium needs
I would recommend keeping Tylochromis only if you can offer them a tank of at least 250cm long, as they need a lot of swimming space. I also found out that Tylochromis like to have a strong current in their biotope, so this should be provided.
For a substrate, a thick layer of sand mixed with fine gravel will suffice. A few stones (I chose Basalt stones as they are also present in the Congo River) and some tangles of wood will complete the aquarium. Aquatic plants are possible and will be largely ignored; think Anubias, Bolbitis, Crinum and even Vallisneria.
Adult and dominant males are territorial and will sometimes hunt down congeners. The hunting distance is about two meters, after which the chasing stops. Furthermore, one should always ensure that the water quality is good. In this case, clear water with little or no suspended matter should be provided, something that can be easily achieved with a large and capable filter. My internal filter passes about 10,000 litres per hour, which directly provides the necessary flow in the water.
It is possible to house other fish with Tylochromis lateralis. I myself have done so with Pelmatochromis nigrofasciatus and Pelmatolapia mariae. Both species were tolerated without any problems.
However, fish from other genera such as Auchenoglanis, Mastacembelus, Tetraodon and even mormyrids can also be kept together.
When it comes to feeding, almost all kinds of foods offered are accepted. I feed pellets, flake food (Spilurina and ordinary flakes but large flakes), adult Artemia, Mysis, and both black and white mosquito larvae. As Tylochromis species are sand sifters, they always spend some time shovelling through the substrate after feeding, where scraps are still present. So, it’s no problem at all to offer finer foods, as they search the bottom anyway.
Slow growers
In a little over two years in their huge tank, my fish have grown to between 12cm and 18cm. My experience suggests that they all grow slowly and therefore only show their true colours relatively late in life.
Still, as my fish were growing, I could observe differences between them, indicating that I had different sexes. In the largest specimen, I could increasingly see a blotch and stripe pattern in the tail fin, which was a suggestion that this had to be a male specimen — I found out in work done by Melanie Stiassny that males have this pattern in their tails.
When Tylochromis young are spooked they head for the clearly visible red spot, and thus into the mouth in and away from danger
On the head, just behind the gills, I also noticed a dark vertical band.
In the other specimens, I saw no such changes, so I hoped that these would be females, something that was later confirmed. In at least one specimen, I could see a red colored spot in the corners of the mouth.
Breeding
Since there have been very few aquarists who have kept Tylochromis, it is unsurprising that there is no information available on breeding. Here again, I had done some research, but to no avail.
So, what I tried to do was to imitate the natural conditions as closely as possible. The biggest problem for me was (and still is) obtaining water with a pH value of 5 to 6 and a low conductivity of 50-100μS.
My water values were as follows: a pH of close to 7.0 and a conductivity of approximately 200μS. These values were thus very different from the values in which these fish occur in nature (pH 4.5 to 5.5 and a conductivity from 40 to 70 μS ).
But in spite of that, I tried to let my Tylochromis lateralis reproduce in it, and I can proudly report that I succeeded in breeding them for the very first time in captivity.
Display and deposition
The courtship and reproduction period is announced by the male digging a sand crater nest in an open area of the aquarium, much like the nests of the Tanganyikan cichlids of the genus Opthalmotilapia.
The male starts to show his beautiful colours, especially across the head, in the run up to the courtship. With a trembling body and spread fins, the male swims in front of the female and steers her towards the nest.
When the female is ready, she follows, and then they start laying eggs. The eggs are laid in groups of three to six on the sand, after which the male immediately fertilises them and the female then takes them in her mouth. This is repeated several times and, depending on the size of the female, some 30-50 eggs will be laid.
Tylochromis lateralis is an ovophile mouthbreeder, meaning that the female takes the relatively large fertilized eggs (roughly 3mm in size) in her mouth and incubates them there until they are able to swim freely. Only then the female releases the youngsters into the immediate environment. At the point of release, the fry measure about 10-12mm.
The gestation period of the eggs and larvae until the female releases the young depends on the water temperature and the other fish in the aquarium. If these fish are perceived as a threat after the full gestation period, the female will keep her young in her mouth as long as she can. But in general, the breeding time is about 17 to 18 days (at least, this was the case in my tank) at a water temperature of around 24C.
The rearing of young Tylochromis proved to be no easy task. It appeared to me that much like the parents, the young need clear and acidic water. If this is not provided, they will slowly but surely die.
Just as important is the need to feed juveniles often, especially during the period of growth up to around 4-5cm, and that requires a mainly vegetable diet. When the juveniles have reached a length of 5-6 cm, they are less sensitive and can tolerate more variety in both food and water conditions.
If all the above-mentioned preconditions are adhered to, every aquarium enthusiast will enjoy keeping Tylochromis lateralis.