Category: Cichlids

African, South and Central American Cichlids

What’s New In Cichlid Studies: Part 2


The greatest challenge in spawning cichlids in the home aquarium seems to be getting the pair to do their business and churn out the fry. Assuming one has a male and a female, which is not always easy to select in some species, the problem is to ensure that they mate and produce fry without killing each other. Aquarists often try to breed a pair of cichlids in an isolated tank. This may be necessary if the only available tanks are too small to sustain a community of fish. Given a large enough tank, however, it is known that it is often easier to breed cichlids if there are some dither fish with them.

Dither fish may be other cichlids of the same or different species, but need not be. They can be cyprinids or other speedy fish that distract the breeding pair’s aggression from each other and focus it outward against the dither fish. It was recently demonstrated with experiments on angelfish that pair bonding is maintained when there are intruders to defend the nest against [1]. Monogamous marriages among angelfish are the result of a mutually defended territory, not an altruistic feeling.

Aquarists often have trouble selecting a male and a female of a cichlid species. The best method is to raise up six fry and let them do the selecting, but that is not always possible. Even for the fish themselves, they sometimes have trouble. This was shown with a study on three closely related Lake Malawi cichlids where males were isolated from various females by glass so they only had visual cues to go by. Pseudotropheus males in the study could identify females solely by sight in some species, but in other species the males were unable to correctly select females by sight alone [2]. This suggests that olfactory cues, that is, the scent of the females in the water, may play a part in pair formation. Sound production was ruled out in this experiment, but it is known to be used by other cichlids. Given that even the males (who should know) have trouble identifying their own female conspecifics, it is not surprising that aquarists trying to do their own matchmaking have hybridized Pseudotropheus species unwittingly. All those bland females look alike but are not alike in the gene pool.

Courtship may involve sounds, although aquarists may not be able to hear the serenades. The males of two Malawi cichlids are known to produce pulsed sounds while courting females, those being Tramitichromis cf. intermedius and Copadichromis conophorus [3].


One peculiarity of some Tanganyikan cichlids is that juveniles will help older fish raise fry, such as assisting in mutual defence of territory. Neolamprologus brichardi is well known for this behaviour. A swarm of such fishes on a rock pile consist of parents, their young fry, older juveniles, and unrelated juveniles from elsewhere. Such altruism gives the brood care helpers experience in learning to raise children for when their own time comes. Aquarists should not be too hasty in breaking up hatches of such fish if all else is well. Indeed, what may contribute to cichlid mayhem and murder in aquaria, besides too-small tanks, is that many fry are siphoned out and raised separately. They never learn the social cues that enable fish to get along, much as the problem with most human juvenile delinquents is that they are from broken homes where they never learned proper behaviour. When they are sold off and placed in new homes, the isolated fry cause difficulties in breeding.

Sometimes altruism in habitat loses precedence to selfish DNA. Neolamprologus brichardi juveniles greater than 4.5 cm standard length are mature. Mature enough, in fact, to take an interest in the lady of the house, just as a human boarder may cuckold the landlord with his wife. Such fish will try to parasitize the spawning of the parents. Even if they only succeed in fertilizing a few eggs, that is better than nothing. The male of the pair does not take this lightly, anymore than a landlord would when he finds his wife in bed with the boarder, and the parasitic breeder will be driven out of the rock pile. The study that uncovered this determined that 4.5 cm is the boundary line before such a thing happens [4]. From a practical point of view for the aquarist, it would therefore seem logical to start taking out juveniles at that length or perhaps even 3.5 cm, which is the length at which Neolamprologus brichardi is sexually mature.

Mixed schools of fry may not only contain fry from different parents but also different species. The Tanganyikan cichlids Lepidiolamprologus elongatus and Perissodus microlepis often have 20% to 40% foreign fry of other species in their schools [5]. The parents are well aware of them but seem to tolerate them because the hassle of trying to evict foreign fry would attract the attention of predators. It would not be easy tracking and chasing one certain fry in a cloud of them and killing or evicting them.


A basic principle of ecology is that the more closely two species live in similar habitats, the more antagonistic they are to each other. An algae scraping cichlid does not worry about a mid-water feeder, and a cichlid that munches on snails is not upset to see an algae feeder nearby. (This assumes no breeding territorial functions are involved; if fry are being protected, then parental instincts override feeding behaviour.) For very dissimilar species, scientists have no trouble establishing this principle. Things get complicated when apparently similar species tolerate each other in the same territory. Is this because scientists haven’t identified the different behaviours (which have only micro-differences)? Or is it because the fish really use the same behaviour and the theory is wrong?

The Rift Lake cichlids have attracted scientific attention on this point because of similar species co-existing. One case study involved Lobochilotes labiatus, a Tanganyikan crevice feeder [7]. These fish have large fleshy lips; they suck shrimp, mayfly, caddis fly, and midge larvae out of crevices. Feeding territories of similar-sized fish do not overlap, which is expected, since they would be competing for food. However, there was little aggression between large and small individuals. Analysis showed that the large fish worked large crevices and the small ones worked small crevices, thus separating their feeding microhabitats even though they overlapped on a larger scale. The difficulty in determining overlaps or not was seen in another study on a number of Lake Malawi cichlids [6]. Many species apparently co-exist despite using the same feeding niches, although most differentiate their food sources. Further study will be required in habitat.

But further study can also be done by aquarists. Granted that a home aquarium is not a true representation of a Rift Lake; the biggest, most sophisticated aquarium can never fully duplicate wild conditions. But that is no reason not to study your fish and observe what they are doing. Professional ichthyologists will never be able to examine the behaviour of all the cichlids. Aquarists can fill in the gaps. Home research may not be as rigorous as professional research, but it can often suggest leads for others to follow. This does require communicating what you have learned in watching fish, the easiest way of which is to write up your observations for your club bulletin. Since most clubs exchange with others, your article will be read by more people than you imagine, and some of them are ichthyologists.


1] Yamamoto, M.E., S. Chellappa, M.S.R.F. Cacho, and F.A. Huntingford (1999) Mate guarding in an Amazonian cichlid, Pterophyllum scalare. JOURNAL OF FISH BIOLOGY 55:888-891

2] Knight, M.E., and G.F. Turner (1999) Reproductive isolation among closely related Lake Malawi cichlids: can males recognize conspecific females by visual cues? ANIMAL BEHAVIOUR 58:761-768

3] Lobel, P.S. (1998) Possible species specific courtship sounds by two sympatric cichlid fishes in Lake Malawi, Africa. ENVIRONMENTAL BIOLOGY OF FISHES 52:443-452

4] Dierkes, P., M. Taborsky, and U. Kohler (1999) Reproductive parasitism of broodcare helpers in a co-operatively breeding fish. BEHAVIORAL ECOLOGY 10:510-515

5] Ochi, H. and Y. Yanagisawa (1996) Interspecific brood-mixing in Tanganyikan cichlids. ENVIRONMENTAL BIOLOGY OF FISHES 45:141-149

6] Genner, M.J., G.F. Turner, and S.J. Hawkins (1999) Foraging of rocky habitat cichlid fishes in Lake Malawi: coexistence through niche partioning? OECOLOGIA 121:283-292

7] Kohda, M. and K. Tanida (1996) Ovelapping territory of the benthophagous cichlid fish, Lobochilotes labiatus, in Lake Tanganyika. ENVIRONMENTAL BIOLOGY OF FISHES 45:13-20 ?

What’s New In Cichlid Studies: Part 4


One of the basic stumbling blocks facing aquarists trying to spawn their cichlids is the difficulty in getting a breeding pair. Trying to identify which is the male and which is the female is not always easy. Some species are dimorphic, with obvious males and females, usually due to coloration or shape. Others lead aquarists into frustration trying to determine if they have a pair or if they are just wasting fish food on two of the same gender.

Recent evidence is suggesting that it is not always the aquarist’s fault in not being able to identify gender in cichlids. Some cichlid species are known to be able to change gender as a result of environmental conditions around them. The Midas cichlid Cichlasoma citrinellum, for example, develops as a female by default but changes into a male during juvenile development based on its relative size to other juveniles in the brood [1]. Males are larger in this species.

This justifies the traditional advice that if you can’t buy a known breeding pair of cichlids, then get a half dozen young and let them sort themselves out as they grow up. This advice was actually based on probability odds, as out of six fish there is a very strong chance that at least one pair exists. Now one can see the other reason, for if gender can be altered during maturation, then at least one cichlid might switch to a male if all of them are default females to begin with.

Another study using Crenicara punctulata verified this, where it was confirmed that the dominant female in a batch of juveniles will become a male [2]. A female in isolation will turn into a male.

The tilapia Oreochromis mossambicus has its gender determined during its first ten days of life [7]. If during that time, the larvae are in cool water (20o to 24oC), most of them will develop as females. In warmer water (28C to 32C) they will be mostly males.

As anyone knows who reads the aquarium literature, there is all manner of conflicting advice and non-reproducible experiments in the hobby. It can be seen that part of the confusion on how to select and maintain breeding pairs comes about because the aquarist writing the article may not be aware that one or more of the fish has changed gender. It’s enough to make one take up stamp collecting instead.


As stocks of wild-caught cichlids dwindle from habitat extinction, it becomes more important to maintain breeding stocks in captive populations. One problem is the loss of genetic diversity in captive stocks, and the accumulation of defective or sickly individuals. This is often blamed unfairly on inbreeding, but aquarists should realize that inbreeding is neutral. The reason that it gets blamed is because those doing the inbreeding fail to cull out the inadequate fry. Lethal or sub- lethal traits then accumulate, and the problem is then unjustifiably said to be ‘inbred fish’. All breeds of domesticated animals, whether they be Charolais cattle, German shepherds, or roller canaries, were initially established by inbreeding for desired traits. Unfortunately, too many fish breeders can sell whatever they produce no matter what garbage the fish are, which is why you see parrot cichlids and crick-back goldfish in pet stores. But it is not the fault of inbreeding per se, just the failure to select and cull.

Decline in genetic diversity is a more serious problem. It should be understood that low genetic diversity does not mean subnormal quality. Animals in a low-diversity population can be quite healthy and vigorous. However, when the environment changes, or a new disease sweeps through, high genetic diversity allows the species to survive no matter how great the mortality rate. Random variability of the genes ensures that at least a few of the individuals happened to have resistance.

In the aquarium hobby, it is therefore important to maintain high genetic diversity within a species population. The average aquarist cannot maintain large stocks of a species, though. This eliminates the idea of keeping genetic diversity high by the brute-force method of having thousand of cross-breeding individuals. Zoos get around this problem by regularly exchanging individual animals between themselves to keep the genes flowing between sub-populations.

A recent study on haplochromines out of Lake Victoria, carried out at the Ohio State University, showed that the best procedure to keep a cichlid population diverse is to periodically remove dominant males and to maintain more sub-populations [6]. Removing a dominant male after he has bred a few times will allow another male to get a chance to spread his genes about. Sub-populations are subject to random mutation of genes, which then have a better chance of establishing instead of being swamped in one large population.

Genetic diversity doesn’t just mean color patterns or shape. It also means resistance to disease or environmental shock. Behaviour is known to be an inheritable trait. There are many other traits invisible to the aquarist but which have a very real impact on the population.


The reputation of cichlids for nasty behavior is more the aquarist’s fault than the fish. In the wild, the loser of a fight flees the scene and there are seldom fights to the death. In the aquarium, the loser can’t get away, which frustrates the winner and escalates what would have been a brief skirmish into deadly combat.

How do winners know they have won? Obviously, the loser backs off, but another reason is color change. Losers often change color and pattern to submissive or at least aggression- inhibiting colors. An example recently studied is the oscar Astronotus ocellatus, where the loser goes to near black body color with irregular white bars [3]. This sends a signal to the victor, and cools him down.

Victors of a fight have no reason to continue it out of spite, for injuries and wasted metabolism of food energy can be costly to them, albeit not as much as to the loser [4]. The winner of a fight must expend energy that could be used for other things such as spawning or building up food reserves. If a winner continues to beat up a fish in a tank, it is because it is not perceiving that it has actually won the contest. Depending on the species, it may expect submissive coloring from the loser or for the loser to leave the scene. Aquarists who have trouble with murder and mayhem in the tank should bear this in mind, and look to remedies such as netting out the loser. Don’t make life hell for both of them by leaving them jammed in together in a glass box that is obviously too small for them.


Cichlids are the most speciose group of fish, particularly in eastern Africa. There has long been controversy as to why this would be so. The countless color patterns of Rift cichlids have been the obvious point of departure for enquiry, but experimental results have been confusing and contradictory. Wallace Dominey published an hypothesis in 1984 that speciation was driven by sexual selection, which is to say that females prefer bright colorful males of a certain pattern.

While this is believed to be true in general, there have been exceptions. A new study by a group of Dutch ichthyologists at the University of Leiden [5] suggests that the problem in understanding cichlid colors is that each species has two sets of colors and patterns evolving under different pressures. Nuptial or breeding colors are based on sexual selection, where the prettiest male gets the females. Vertical bars, however, are camouflage for structurally complex habitats such as rock piles. Horizontal stripes are associated with piscivorous feeding and/or shoaling behavior. Sexual selection has no effect on bars or stripes. This would therefore explain why previous studies have been at odds with each other, because they thought all three sets of patterns and colors were one.


1] Francis, R.C., and G.W. Barlow (1993) Social control of primary sex differentiation in the Midas cichlid. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES USA 90:10673-10675

2] Carruth, L.L. (2000) Freshwater cichlid Crenicara punctulata is a protogynous sequential hermaphrodite. COPEIA 100:71-82

3] Beeching, S.C. (1995) Colour pattern and inhibition of aggression in the cichlid fish Astronotus ocellatus. JOURNAL OF FISH BIOLOGY 47:50-58

4] Neat, F.C., A.C. Taylor, and F.C. Huntingford (1998) Proximate costs of fighting in male cichlid fish: the role of injuries and energy metabolism. ANIMAL BEHAVIOUR 55:875-882

5] Seehausen, O., P.J. Mayhew, and J.J.M. Van Alphen (1999) Evolution of color patterns in East African cichlid fish. JOURNAL OF EVOLUTIONARY BIOLOGY 12:514- 534

6] Fiumera, A.C., P.G. Parker, and P.A. Fuerst (2000) Effective population size and maintenance of genetic diversity in captive-bred populations of a Lake Victoria cichlid. CONSERVATION BIOLOGY 14:886-892

7] Wang, L.H., and C.L. Tsai (2000) Effects of temperature on the deformity and sex differentiation of tilapia, Oreochromis mossambicus. JOURNAL OF EXPERIMENTAL ZOOLOGY 286:534-537 ?

What’s New In Cichlid Studies: Part 3


Cichlidae is among the most speciose fish families in the world. Their diversity is especially wide in Africa. Zoologists are therefore understandably curious to know why this is so, and why the speciation happened so fast, since some of the great African lakes are less than one hundred thousand years old.

Among the obvious suspects is geographical discontinuity. Populations are more likely to differentiate into new species when they are confined to a small area and prevented from interbreeding with other populations. The barriers do not have to be absolute, as species will still develop even if there is a small amount of genetic interchange. This also applies to species developing as a result of specialising in different food types, where there can still be a bit of overlap in diet during speciation [6]. A third method of speciation, demonstrated in Lake Victoria cichlids [7], occurs when gender preferences for colour displays drifts apart. One group of males tends to prefer a certain pattern displayed on another group of females, another group a different pattern, and so forth. The incipient species may still interbreed, but as time goes by they can drift apart genetically into distinct species, purely on the basis of mating habits, not food niche or isolation. This is not a case in which a new species suddenly occupies one certain area, or eats only a certain food that no other cichlid does.

One stumbling block faced by zoologists is that first the researcher must determine what species are in the study area. It is seldom the case that there are clear and distinct fish. More commonly a continuum of populations exists where the fish at either end are obviously different but there is a gradual transition in between. Aquarists will receive the extremes of wild fish from collectors and think of them as distinct, yet someone who sees them in habitat will not be so confident.

Labeotropheus fuelleborni is a Lake Malawi cichlid kept by many aquarists. A study published in 1999 showed that this cichlid migrates readily enough along rocky shorelines, but more than two km of sandy beach or deep water will intimidate it and act as a barrier to gene flow. The study was carried out along the Nankumba Peninsula shoreline at the south end of Lake Malawi [1]. Males at the northwest end of the peninsula were darker blue with darker grey bars, while males at the south-east end were lighter in colour with stronger red-orange fin pigmentation. It can be seen that the fish are two extremes of a single species, but if isolated by geographical change long enough, they would eventually develop into distinct species.

In the aquarium, such extremes are often considered as two species. Against this, however, “interbreeding” in the tank has been common, especially where the females are drab and easily confused. A lost cause of the American Cichlid Association is its valiant fight to eliminate cichlid hybrids from the hobby. The danger of hybrids is that by muddying the gene pool they make it impossible to reconstruct the original species by line breeding. This never used to matter because aquarists could start over again with freshly imported specimens from habitat. Now in some cases those specimens are gone, because the wild species has been wiped out. The most prominent examples of this are the Lake Victoria cichlids, exterminated by the introduction of Nile perch into the lake.


Cichlids have a general reputation for being aggressive in the home tank, but I think this unfair. In habitat, aggression seldom leads to fatal consequences because the loser can flee the area. This is not possible in the aquarium. The two most common reasons for this are that the tank is too small and that the aquascaping allows one or a few fish to dominate the entire tank.

Just how much room is needed can be estimated from studies such as one carried out on Lamprologus ocellatus, a snail-dwelling cichlid. The male keeps a harem of females. He prepares empty snail shells, keeping one or two open and burying the others nearby for future use. The largest female will dominate the harem and will be quite intolerant of other females. In habitat, the females of a harem will establish themselves about 90 cm apart [4]. One can see that this would not be possible in the average home aquarium, but aquascaping to block females’ views of each other could allow a small harem. Otherwise the tank may only support a single pair of fish, rather than a harem. Whatever the case, it is easy to see that in habitat the snail cichlids have room to spread out, but in a small tank they end up killing each other because the losers can’t get away. From this is then made the claim that “cichlids are aggressive”. Confine six aquarists in a small utility room and see if they don’t become aggressive as well!

In the converse, however, it will not pay a cichlid to have too much territory, more than it can reasonably defend. A study on convict cichlids (Cichlasoma nigrofasciatum) showed that large cichlids defend food patches against smaller convicts, and experience a growth surge because of the better food supply. The food patch can be so large that the owner spends more time defending it against intruders than enjoying the benefits. As a result, the growth rate of the convict declines because it is using up too much energy [5]. In habitat, cichlids must obtain an optimal sized territory. Too small, and it won’t provide a living. Too big, and it will be indefensible. The cichlid must strike a balance between food and energy expended in defence. By extrapolation, in the aquarium, fish which spend most of their time defending territories are burning up energy which could be used for breeding. Something to think about when stocking a tank or wondering if it should be culled.


It is not unusual for parental cichlids to be guarding fry of other parents, or even other species. Some cichlids, such as the Tanganyikan Microdontochromis, actually release their fry into other broods not even the same species [2]. Lamprologus ocellatus females are known to accept other fry if they are not too dissimilar and are smaller than hers [4]. Smaller, because large fry will cannibalise small fry if the size difference is too great. For those aquarists who want to maximise their output of spawns, this suggests that fry should regularly be culled and sorted on the basis of size, to keep each group at about the same average size and thereby avoid cannibalism.

One might expect parents to resent such unwanted foster care, but, without being able to read the thoughts of a cichlid, there seem to be some reasons why this is tolerated. To pick out individual fry in a swarm is a difficult energy-consuming task, one which would also attract the attention of predators who would swim over to see what all that thrashing is about. (Predators are often attracted to thrashing because that may indicate a prey in trouble and thus easier to take.) The dilution effect reduces the chances of a parent’s fry being taken by a predator. If, for example, one-third of the cloud of fry are not the parent’s fry, then the odds are one-third that a predator will snatch someone else’s kid.


Mouth brooding cichlids normally don’t eat while carrying fry. This is not an absolute rule, as Microdontochromis is known to be able to feed and brood simultaneously [2]. The parent feeds on zooplankton floating through the water, and so do the brooded fry, thus enabling them to grow bigger and faster.

Aquarists dealing with a newly-obtained cichlid for which they are unable to find information can often determine what type of food it eats and how it eats by looking at the mouth structure. Aquarists often forget that it is important to know not only what type of food the fish eats, but how it eats. A mid-water feeder will ignore the algae growing on a rock, while the algae scraper depends on that food source. Algae biters have stronger jaws, such as the Lake Victorian haplochromine Neochromis [3].

Quality of the food makes a difference not only to the general health of the fish but to its success in territorial defence and breeding ability. It is common in many species for the female to chose a more brightly coloured male, all else being equal, because the pigmentation of fish depend on their diet. The better the diet, the brighter the colours. The brighter the colours, the better the male must be as a father. It isn’t just humans who judge by image!

This was demonstrated by a study on male fire-mouth cichlids (Cichlasoma meeki) where half the test fish were given a high-carotenoid diet and the other half a low-carotenoid diet [8]. The more carotenoid, the brighter the red pigment of the fish. The brighter the fish, the more likely it was to win aggressive interactions with other males.


1] Arnegard, M.E. et al (1999) Population structure and colour variation of the cichlid fish Labeotropheus fuelleborni Ahl along a recently formed archipelago of rocky habitat patches in southern Lake Malawi. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON 266B:119-130

2] Yanagisawa, Y., H. Ochi, and A. Rossiter (1996) Intra-buccal feeding of young in an undescribed Tanganyikan cichlid Microdontochromis sp. ENVIRONMENTAL BIOLOGY OF FISHES 47:191-201

3] Bouton, N., F. Witte, J.J.M. van Alphen, A. Schenk, and O. Seehausen (1999) Local adaptations in populations of rock-dwelling haplochromines (Pisces: Cichlidae) from southern Lake Victoria. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON 266B:355-360

4] Brandtmann, G., M. Scandura, and F.Ttrillmich (1999) Female-female conflict in the harem of a snail cichlid (Lamprologus occellatus): Behavioural interactions and fitness consequences. BEHAVIOUR 136:1123-1144

5] Praw, J.C., and J.W.A. Grant (1999) Optimal territory size in the convict cichlid. BEHAVIOUR 136:1347-1363

6] Genner, M.J., G.F. Turner, S. Barker, and S.J. Hawkins (1999) Niche segregation among Lake Malawi cichlid fishes? Evidence from stable isotope signatures. ECOLOGY LETTERS 2:185-190

7] Seehausen, O., J.J.M. van Alphen, and R. Lande (1999) Color polymorphism and sex ratio distortion in a cichlid fish as an incipient stage in sympatric speciation by sexual selection. ECOLOGY LETTERS 2:367-378

8] Evans, M., and K. Norris (1996) The importance of carotenoids in signaling during aggressive interactions between male firemouth cichlids (Cichlasoma meeki). BEHAVIORAL ECOLOGY 7:1-6 ?