With the exceptions of Hemichromis thomasi and Tilapia ruweti, the African riverine dwarf cichlids are representatives of genera composed entirely of species that satisfy the definition of this group I proposed initially (Loiselle, 1979). To wit, they must be species in which the female, should sexual dimorphism obtain, does not exceed 8.0 cm SL, capable of coexisting peacefully with non-cichlids of approximately the same size and like to spawn successfully in a tank of 60 l capacity. Among the dwarf cichlids of Lake Tanganyika, this pattern is reversed. Only the three genera of goby cichlids comprise exclusively dwarf species. The remainder are dwarf representatives of genera containing species that fall well outside of even the rather flexible boundaries of this group. Not by the remotest stretch of the imagination is anyone likely to mistake Lepidiolamprologus attenuatus or Telmatochromis caninus for a dwarf cichlid! The Tanganyikan dwarf cichlids are also the only representatives of this group that include mouthbrooders among their number, though as it will soon become evident, mouthbrooders whose behavior is, in rnany respects, dramatically different from that which aquarists have come to associate with this particular reproductive modality. However much these little cichlids may differ from one another in morphology, habitat preference, and reproductive behavior, their common origin imposes a common approach to their successful maintenance. Tanganyikan cichlids resemble marine fishes rather than riverine or even other lacustrine cichlids in their intolerance of abrupt environmental fluctuations. This is due in large measure to both the great age and the markedly oceanic character of Lake Tanganyika itself. This vast body of water, 640 km long with an average width of 40 km, has a maximum depth of 1600 m over a mile. Such a huge volume of water is virtually impervious to short-term physical or chemical changes. Temperature variation in the upper layers of the lake range over less than 3°C. annually because the deeper waters act as an enormous heat sink. As for changes in water chemistry, how can any but the most trivial local fluctuations occur in a lake where the yearly inflow of water from the surrounding drainage area is only 1/1500 of its total volume? This picture of long-term stability with respect to temperature and water chemistry contrasts dramatically with the markedly seasonal regimes prevailing in tropical streams in both Africa and South America. Here water temperatures can drop 3°C. within a few hours of an upstream cloudburst capable of generating flood conditions that abruptly alter pH, hardness and dissolved oxygen values.
Riverine dwarf cichlids, faced with such large-scale, short-term fluctuations in the character of their habitats on a regular basis are, of necessity, fairly flexible in their ability to withstand comparable conditions in captivity. Thus, while they are intolerant of dissolved metabolites, they respond well to management approaches based upon regular, fairly massive water changes. Tanganyikan dwarf cichlids, on the other hand, are the products of near onto ten million years of evolution in an environment effectively buffered against short-term fluctuation. In the course of their evolution, these lacustrine cichlids have largely lost the capacity of their riverine ancestors to cope with such changes in their immediate milieu. They have not, however, lost their intolerance of dissolved nitrogenous wastes in the process. This tends to make maintenance of suitable living conditions for them in captivity something of a challenge.
Keeping Tanganyikan cichlids, be they large or small, happy under aquarium conditions requires a cichlid enthusiasts to adopt much the same approach towards aquarium management that characterizes the successful marine aquarist. The objective in both cases is to avoid traumatic environmental change. This is a fairly simple matter as regards water temperature. Any good thermostatic heater will keep tank temperatures from fluctuating more than a degree Celsius from its predetermined setting. Managing the nitrogen cycle is a bit trickier, for it entails never allowing dissolved metabolites to build up to toxic levels. This dictates light stocking in conjunction with either efficient biological filtration or mechanical filtration combined with regular changes of no more than 25% of the tank volume at one time. The use of chemically filter media such as Poly-Filter in conjunction with mechanical filtration provides a useful buffer in the event that a regular water change is missed or some accident results in pollution of the aquarium. Both approaches have been applied to the maintenance of Tanganyikan dwarf cichlids. In view of the fact that these fish spawn with equal alacrity and regularity regardless of the approach employed, it seems reasonable to conclude with the observation that the choice of approach may be safely dictated by each aquarist's personal circumstances.
The water of Lake Tanganyika is hard and alkaline, and cichlids from the lake demand comparable conditions in captivity. With pH values of 8.5 to 9.0 and hardness in excess of 400.0 ppm TDS, Lake Tanganyika water can be something of a challenge to duplicate. The process is least troublesome in areas of naturally occurring hard water. Here little more is required to maintain suitable conditions for these cichlids beyond adding a layer of crushed dolomite or oyster shell to the filter. Many aquarists utilize such materials in conjunction with an undergravel filter in place of the standard quartz or flint aquarium gravel. This does not always produce the desired objective. The development of the bacterial flora necessary for the proper functioning of such a filter effectively masks the surface of the particles comprising the filter bed. This precludes significant chemical interactions with the water from occurring. A lesser quantity of either substance spread as a thin layer in a filter box and washed regularly is far more effective in buffering the water. In areas where the water supply is soft, the use of commercial Tanganyikan salt mixes will recreate suitable water conditions for these cichlids. Their one shortcoming is the limited solubility of the carbonates that comprise their major constituents. It typically takes three or four days at 25°C. for such salts to go completely into solution. This dictates careful advanced planning of water changes.
The Tanganyikan dwarf cichlids have several other common maintenance requirements. The first is quite simple, if not intuitively obvious: a tightly fitting cover glass. All of these fish have a positively preternatural ability to find their way out of seemingly impassable crevices between tank frame and cover glass. The usual motivation for so emulating a Poseidon missile is an understandable desire to escape the gentle ministrations of a tankmate. As a fish can have no way of knowing that its keeper will intervene on its behalf as soon as such harassment is noticed, such behavior is understandable. I can attest from personal experience, however, that knowing why the female of a prized pair of fish opted for mummification provides scant consolation after the fact! So keep these fish tightly covered and avoid that gut-wrenching sensation that follows discovery of only one fish swimming where two ought to be.
Secondly, all of these fish are highly territorial. The focus of such behavior is typically a permanent shelter that in substratum-spawning species also serves as a spawning site. Conspecifics are invariably excluded from this territory with lethal efficiency. It might seem impossible for any fish with the mouth structure of a Julidochromis or Tanganicodus to seriously injure, much less kill a conspecific. Yet the behavior of these fish is such that it is rarely possible to maintain more than a single pair per 60 100 L aquarium. Coexistence of multiple pairs in larger aquaria is largely determined by the amount of available cover. The more shelter available, the less risk of intramural thugee. Fortunately, these fish seem well able to coexist as single pairs on a long-term basis, a fact that also makes it fairly easy to manage the light stocking rates required to keep dissolved metabolite concentrations at an acceptable level in their aquaria.
Midwater living fishes are typically ignored by these cichlids. Indeed, like other dwarf cichlids, these Tanganyikan species are usually much less retiring when housed with such dither fish. Medium-sized poeciliids and the less aggressive goodeids make excellent companions for these cichlids, as do rainbowfishes of the Family Melanotaeniidae. Bear in mind that these cichlids vary considerably with respect to their competance as piscivores. Hence human intervention may be required to keep the cichlids from drowning in dither fry. Such a superfluity of dither not only provides more competition at feeding time than is desirable, but also can result in predation levels high enough to preclude successful reproduction by the cichlids. This is particularly true if goodeids are used as dither.
All of these little cichlids are invertebrate feeders in nature. They are not picky about meals in captivity, taking all the usual live and prepared foods enthusiastically, though some care should be taken to assure that individual food items are small enough to be conveniently swallowed. Tubifex worms are not recommended for any of these cichlids, as there is a consistent positive correlation between their presence in the diet and the incidence of systematic bacterial infections. Artemia nauplii are an excellent and easily produced live food for both the fry and adults of these cichlids.
The genus Julidochromis is, in all respects, the logical starting point for any consideration of the Tanganyikan dwarf cichlids. Julidochromis ornatus Boulenger 1898 is the aquaristic doyen of the group, having made its aquaristic debut in both the United States and Germany in 1958. According to Vierke (1979), this importation resulted in the establishment of a viable aquarium strain of this beautiful little cichlid in Europe. Though it was also successfully bred in the United States, J. ornatus did not become established here until the late 1960's. This may be difficult to believe in view of the small size and vivid coloration of this fish, but skeptics should recall that this all occurred before the Malawi Revolution made cichlids respectable as aquarium residents and hence of interest to wholesale and retail dealers alike. All the dwarf Julidochromis are commercially available at present. Indeed, in the United States, they are easily the most readily available Tanganyikan dwarf cichlids. The likelihood that readers are most apt to encounter these fish is yet another reason for giving them priority of coverage.
The genus comprises five described species. Two of these, Julidochromis regani Poll 1942 and Julidochromis marlieri Poll 1956 grow to 15.0 cm SL. While both species make satisfactory community residents and young pairs will spawn in tanks of 60 -100 L capacity, they eventually outgrow such quarters, as much because of their greater fecundity as their large adult size. They, thus, fail to qualify as dwarf cichilds as I have defined them in this series. This caveat aside, they are highly desirable aquarium residents whose successful management differs from that of their smaller congeners only with regard to the dimensions of their quarters.
According to Brichard (1978), all the dwarf Julidochromis are highly petricolous fishes. They are commonly found in rocky biotopes down to depths of 35 m, though they are most abundant in water less than four meters in depth. They are strongly site-specific little cichlids, rarely moving more than a few meters from a permanent shelter, which must make collecting them a rather interesting proposition! The members of this genus are the only cichlids for which there is any evidence of a life-long pair bond in nature. Because these cichlids display considerable individual variability in color pattern, recognition of idiosyncratically marked individuals in the field is quite feasible. Brichard (pers. comm.) reports seeing the same pairs of Julidochromis occupying the same caves over a period of several years. The ease with which it is disrupted by a change of venue (Lewis, 1975; Doyle, 1978) strongly suggests that the basis of such long-term pair bonding is almost certainly the joint defense of a shelter rather than reproduction per se.
There is a widespread belief that Julidochromis reverse the usual pattern of size dimorphism in cichlids, with females invariably growing larger than males. According to Brichard (pers. comm.), this is certainly not the case in Lake Tanganyika, where the larger member of a given pair is generally the male. Lewis (1975) has suggested that this notion is based upon two unrelated phenomena. The first is the presence of a very conspicuous, pendant urogenital papilla in male Julidochromis. Superficially, this can be easily mistaken for an ovipositor. The second is that in captivity, males are the usual victims of domestic violence, with the unavoidable consequence that females of aquarium-held pairs are typically older and hence larger than the males obtained as replacements. Whatever the merits of this most reasonable hypothesis, I certainly do not advise potential purchasers of these cichlids to work on the assumption that the larger fish in a brood of young are inevitably the females when selecting breeding stock.
There is no argument at all over the incidence of netting trauma among julies. Specimens occasionally go into tetanic shock from which they do not recover following capture (White and White, 1977). This is hardly a common phenomenon, nor is it restricted to the genus Julidochromis. The factors that cause it are poorly understood. Such episodes sometimes, but not inevitably, occur after prolonged chases. What does seem to characterize all cases of netting shock is some sort of pre-existing stress on the victim, either physiological or behavioral. The best advice one can offer at this point is to keep stress at a minimum through proper maintenance practices and try to capture fish with as little disturbance as possible. One advantage to maintaining these fish as single pairs in 60 -100 L aquaria is that captures are far more readily managed under such conditions than they are in a large community set-up.
Julies, to give them the name affectionately bestowed upon them by cichlid fanciers in the U.S., otherwise make few demands on their keeper beyond a well-furnished tank. I prefer to use rockwork to attain this objective, but I have seen julies maintained successfully in tanks furnished with sections of PVC pipe or appropriately sized flower pots. Once their requirement for shelter has been met, these little cichlids are easily bred. As with the generality of monogamous cichlids, the secret of success lies in obtaining a compatible pair. The usual approach of rearing a group o young fish to maturity in a large tank works quite well. However, extreme vigilance is required to prevent the first pair to form from liquidating their sibs. Many successful breeders float plastic plants at the surface of the tank to provide cover for the victims of such harassment. Defeated fish typically seek to escape by hovering near the surface of the water. Giving them such hiding places not only increases their prospects for survival but also makes it somewhat easier to net them out once they are noticed. Adult fish will also pair readily in a community situation, though such pairs may prove unstable when transferred to a separate breeding tank. Having dither fish present following such a move tends to minimize the risk of pair fission at this time. Once they have settled into permanent quarters, julie pairs are usually extremely stable. This makes life fairly easy for their keeper once the process of matchmaking has been concluded.
I have never seen any julie courtship more overt than low-level reciprocal opercular flaring and fin erection. This tendency to play down the preliminaries makes it very easy to overlook a spawning. The penchant julies display for depositing their eggs in the most inaccessible crevice available to them hardly simplifies the detection of spawns either. A fairly good clue that something has occurred lies in the female's refusal to leave shelter save to grab a quick bite to eat. Even this behavior may be misinterpreted if the fish are housed under conditions that promote, rather than dispel, their secretive tendencies. The ovoid, rather bilious green eggs measure c. 1.5 mm along the major axis. Compared to those of other substratum-spawning cichlids, they seem to receive shockingly little attention from the female, while the male has nothing to do with them whatsoever. Parental care in julies seems to be almost purely custodial. The hygienic elements so characteristic of other dwarf cichlids are conspicuous by their infrequent occurrence. In spite of this, julie eggs do not respond well to artificial incubation (Brock, 1978). The eggs hatch in 72-80 hours at 25° , and the fry are mobile four days thereafter. There is no overt care of the free-swimming fry by their parents. As long as they stay within the limits of their parents' territory, they are the beneficiaries of its active defense. Otherwise, the breeders effectively ignore them.
The problem most aquarists encounter in their efforts to breed these fish arises from the small size of the newly mobile fry. The dwarf julies are among the very few cichlids whose fry are incapable of taking Artemia nauplii as their first food. If the breeding tank has a well-developed algal carpet on its back and sides and growing over the rockwork with which it is furnished, the breeder is unlikely to notice any problems in his use of nauplii as an initial food. The microorganisms in the algal mat sustain the fry for the first few days of their free-swimming existence. Once the fry have accomplished this initial spurt of growth, they can easily handle nauplii and their rearing poses few subsequent problems. It is only when spawning occurs in a relatively new set-up or when a decision is made to hatch eggs artificially that the inappropriateness of newly hatched brine shrimp as a first food for dwarf julie fry becomes apparent. Both microworms and rotifers are excellent alternatives to Artemia nauplii. I prefer the former, as microworms are far more easily and reliably cultured than is any sort of infusoria. Even with adequate feeding, julie fry grow quite slowly. The young usually reach sexual maturity at 5.0 cm SL, some eight to ten months postspawning.
If not overly protective of their young by cichlid standards, adult Julidochromis do display a remarkable tolerance for their continued presence within the parental territory. It is not uncommon to see an established breeding tank containing young at various stages of growth from wriggler to almost 2.5 cm SL living amicably together with their parents. Such tolerance may have arisen in consequence of the tendency of these cichlids to spread out their reproductive effort over an extended interval. Pairs often produce a clutch of eight to twelve eggs every three to five days. Such an arrangement is workable given the highly attenuated parental behavior of julies, but it cannot function well if the breeders expel earlier progeny from the breeding territory before they are large enough to make it on their own. For their part, the larger fry ignore their younger sibs, though it is well to remember that the more recently produced fry are apt to be at something of a competitive disadvantage at feeding time. A special effort may therefore be in order to guarantee that everyone is adequately fed in such a set-up. It is unwise to impose upon the tolerance of adult julies for their offspring for too long, however. There is a body of evidence suggesting that the stresses imposed by elevated population densities in a breeding tank can disrupt the pair-bond, usually with lethal consequences for the male (Lewis, 1975, 1976). It is a good idea to begin thinning the population out after the appearance of the third or fourth brood of fry.
Just to make life more interesting for the julie breeder, these cichlids have an alternative to continuous spawning, best described as burst spawning. After an interval of reproductive abstinence that can persist for several months, a pair will crank out a single large clutch of up to 200 eggs. Such an event is obviously more convenient to the semi-professional breeder than a succession of much smaller clutches delivered every week over a period of several months. I wish I could supply a recipe for switching Julidochromis pairs from continuous to burst spawning. However, this is hardly possible given that no one has the faintest notion of what environmental factors underlie these alternative patterns. As Brichard (1978) reports the occurrence of both continuous and burst spawning in nature, they clearly are not mere artifacts of captivity. His suggestion that young pairs start out as continuous spawners, then switch over to the burst pattern is appealing, but as he, himself, points out, some pairs never make the switch. It is not unreasonable to guess that food availability is, in some fashion, linked to this dichotomous spawning pattern. Perhaps burst spawning represents a response to an increase in the availability of some critical food item in nature, whose enhanced availability both facilitates maturation of a large batch of eggs while auguring well for the survival of the resulting swarm of fry. When more is known about ecological cycles in Lake Tanganyika, it may be possible to critically test such notions as this with appropriate laboratory experiments. Until then, the problem of switch spawning in Julidochromis must remain another cichlid enigma.
Three Julidochromis species qualify as dwarf cichlids. Julidochromis ornatus, as previously indicated, was the first to be bred in captivity. According to Brichard (1978), this species has a peculiar discontinuous distribution in the lake. The first importation was drawn from populations found along the northwestern coast of the lake, in Zaire. The second known population occurs in the extreme southern end of the lake, in Zambia. According to Vierke (1979), these fish were not imported until 1975. Southern fish are a very pale yellowish-white, in contrast to the northern race's deep yellow base coloration. Both races display an identical pattern of chocolate brown lateral stripes. Anthony J. Piparo of Greenfield, Wisconsin has developed a most attractive albino strain of J. ornatus. This color variety, which made its debut at the 1980 A.C.A. Convention, appears to grow somewhat more slowly than the normally pigmented form, but this aside, seems just as hardy and prolific. Tony is working with the F2 generation and hopes to make fry available soon through commercial channels.
The J. ornatus usually offered for sale today are, unfortunately, quite different from their wild progenitors with respect to both the intensity of their yellow coloration and the integrity of their lateral stripes. Interrupted, or partially fused, stripes are the norm, while tank-bred fish are typically a washed-out beige rather than a deep yellow in color. Many cichild fanciers blame this deterioration on excessive inbreeding. However, the actual culprit is an absence of selective breeding. Aquarists generally are much too lax in their selection of breeding stock and rarely cull deviant phenotypes from the fry they raise for sale or trade. Reluctance to eliminate such standard is even more pronounced when the fish in question is as readily and profitably saleable as are the various Julidochromis species. The temptation to aim for quantity rather than quality in such instances is well-nigh irresistible, but the price of succumbing is the steady deterioration of a species from its original color pattern. Regeneration of the wild phenotype is usually possible given a rigorous program of selective breeding towards that end. Such efforts are time-consuming and few aquarists have the patience to pursue them to a successful conclusion. It is really much easier to prevent the deterioration of an aquarium strain by applying the principles of selective breeding from the outóet thanàit is t/ revers% the effects of many generations of neglect.
Julidochromis transcriptus Matthes 1959, second of the three dwarf julies to be imported as an aquarium fish, enjoys a more extensive distribution within Lake Tanganyika than does J. ornatus. This is reflected in a marked degree of color pattern variability. The more commonly encountered aquarium strains are essentially ivory white with a jet black latticework pattern on the flanks. These individuals are typical of populations of J. transcriptus from the southern end of the lake. These are sometimes sold under the trade name of Julidochromis "kissi." More northerly occurring populations comprise sooty black individuals marked with two parallel rows of roughly circular white blotches on the flanks and a white chin region. According to Brichard (pers. comm.), occasional, almost solid black, individuals of this species are encountered, generally in deep water. Regardless of the arrangement of black and white on the flanks, all J. transcriptus have the same lovely black-rimmed, iridescent blue fin margins that make this species such a desirable aquarium resident.
The third dwarf julie, Julidochromis dickfeldi Staeck 1975, is a recently described species apparently restricted to the extreme southern portion of the lake. Initially imported into Germany, J. dickfeldi made its American debut in 1974 under the alluring designation of "Blue Julie," which rather exaggerates the importance of this element of its color pattern. Probably the most distinctive feature of this julie is the shape of its dorsal fin, whose anterior spines are considerably longer than those located posteriorly. The color pattern is also rather unusual for a Julidochromis in several respects. The cephalic markings in particular are reminiscent of the genus Chalinochromis, which is also apparently restricted to the southern part of the lake. Julidochromis dickfeldi is the least generally available representative of this trio of Tanganyikan dwarfs and characteristically fetches higher prices than either J. ornatus or J. transcriptus. I find this something of a paradox for, to my mind, it is less attractively colored than either of its more readily available congeners.
The name Julidochromis translates literally as "Julis-cichlid." It refers to the remarkable similarity between the enlarged anterior jaw teeth of this group of cichlids and the marine wrasses of the genus Julis. It is the absence of such specialized dentition that immediately distinguishes the superficially similar dwarf Telmatochromis species from their near relatives of the genus Julidochromis. Telmatochromis vittatus Boulenger 1898 and T. bifrenatus Myers 1936 are both slender, relatively small-mouthed species whose retiring behavior as well as their distinctive morphology set them apart from their larger congeners. Telmatochromis temporalis Boulenger 1898 and T. caninus Poll 1942 are robust carnivores with massive jaws. According to Brichard (1978), these species move about freely over a wide variety of substrata, while the two dwarf Telmatochromis are restricted to rocky biotopes, whose shelter they seldom leave. Brichard also notes that while the two large species will spawn successfully in relatively exposed situations, T. vittatus and T. bifrenatus spawn only in caves or crevices with extremely narrow openings. The specialized spawning site requirements of the two dwarf species are indicative of a far less aggressive temperament than that evinced by their more robust congeners. This fact, no less than their attractive coloration, has won them the affection of Tanganyikan cichlid enthusiasts.
The two dwarf Telmatochromis have been confused in some quarters. This is not too surprising given that both species are slender-bodied fish marked with dark lateral stripes on a pale beige to yellow-white background. The situation is further clouded by the fact that populations of both species occur comprising individuals marked with an additional narrow stripe between those present along the dorsum and the midlateral line. This has in some instances led to two-striped individuals of a given species being referred to by one name while three-striped individuals are known by the other. Telmatochromis vittatus is the deeper-bodied of the two species and has a more rounded snout than does T. bifrenatus. The most obvious feature that distinguishes the two species is the zig-zag, or herringbone, pattern present along the posterior third of the flanks in T. bifrenatus. This feature can be seen even in juveniles of that species, but is never present in T. vittatus. Of the two, T. bifrenatus is the more generally available in the United States.
The behavior and maintenance requirements of both dwarf Telmatochromis species are identical in all respects to those of the dwarf julies. They are if anything even more secretive in the placement of their opaque white eggs than are the julies (Cooper and Arment, 1977). The fry are also expert at making themselves invisible for extended periods of time. More than one aquarist has been pleasantly surprised by the seemingly miraculous materialization of a score or more 1.5 cm TL fry in a tank whose inhabitants had up to that point conveyed an impression of steadfast continence! Assuming they are detected at an earlier stage in their development, they should be handled in the same manner as julie fry.
Apart from their extreme intolerance of conspecifics and lack of overt pre-spawning or parental behavior, these justly popular little fish do not deviate dramatically from the popular notion of a dwarf cichlid. The concluding installment of this series on the Tanganyikan dwarfs will introduce two most unorthodox representatives of this group, the shell-dwelling representatives of the genus Neolamprologus and the droll goby cichlids of the genera Eretmodus, Spathodus and Tanganicodus.
- Brock, H.R. Julidochromis ornatus Boulenger 1898. American Cichlid Association Cichlid Index. 3(10): 1-2.
- Cooper, J.R, and H.L. Arment. 1977. Telmatochromis bifrenatus Myers 1936. Amer. Cichlid Assoc. Cichlid Index 2(8); 1-2.
- Doyle, T.W. 1978. A Tanganyika community. Buntbarsche Bull. (74): 16-2l.
- Lewis; R. 1975. And while we're on the subject of Julidochromis... Buntbarsche Bull. (47): 22 et seq.
- Lewis, R. 1976. How many is too many? Buntbarsche Bull. (57): 13-17.
- Loiselle, P.V. 1979. Neotropical dwarf cichlids FAMA 2(10); 22-28 et seq.
- Vierke, J. 1979. Dwarf Cichlids. T.F.H. Publications, Neptune City. White, J. and N. White. 1977. Netting trauma in Julidochromis. Buntbarsche Bull. (60): 19-22.
© Copyright 1982 Paul V Loiselle, all rights reserved
Loiselle, Paul V. (août 27, 1997). "African Dwarf Cichlids, the Lake Tanganyikan Species: Part One". Cichlid Room Companion. Consulté le février 25, 2021, de: https://cichlidae.com/article.php?id=60&lang=fr.