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 ?

Bagging Your Fish for the Auction

Please take the time to bag and label your fish properly to ensure their health / safety enroute to their new homes. Here are a few simple guidelines:

  • Avoid feeding your fish for 36-48 hours prior to bagging. This greatly reduces the amount of waste that will accumulate in the bag while also keeping harmful ammonia levels to a minimum.
  • Use proper fish bags and elastics when bagging your fish (ask for these items at your local aquarium supply shop). Ziplocks are not reliable for holding water and air under pressure so should be avoided. Use ziplock bags only for dry goods… they’re also good for a ham sandwich! 😉
  • Allow for a ratio of approximately 75% air / 25% clean tank water in each bag for maximum oxygen levels and to keep your fish comfortable. The water should cover your fish while the bag is on its side… keep in mind oxygen is more important than water. At this point you could optionally add a small amount of conditioner (or de-stressor) to the water.
  • Use fresh air in your bag – avoid ‘blowing’ air directly into it. Simply open the bag as wide as possible and then quickly snap your hand around the top to seal in a good supply of fresh air. (An air pump could assist.) Use elastics to close the bag, and secure well. The bag should be taut like a balloon.
  • Double-bag your fish if they have sharp fins, teeth or bristles (i.e. anything ‘pokey’). Hint: medium-to-larger-sized cichlids, catfish, sucker fishes / plecos are all common suspects!
  • Always bag medium-to-large fish in separate bags. When deciding how many fish to put together in one bag, consider whether or not they all appear to have enough room (i.e. if the bag were accidentally bumped, would any fish collide with each other?) Fish that are naturally aggressive by nature should be bagged separately (i.e. each aggressive fish gets its own bag!)
  • For any unusually large fish, avoid using fish bags and instead choose a suitably-sized plastic container (pail or bin) with lid to be sold along with the fish. The lid should seal properly but be easily removable in order to properly show the fish.
  • Do your fish take great pleasure in jamming themselves into the corners of the bag? While stuck in a corner of the bag, they may not be able to breathe properly and could injure themselves. A quick-fix to this problem: turn the bag upside-down, and then double-bag for safety. Voila — no more corners!
  • Are your fish accustomed to living in a tank with aquatic plants? If so, adding a small plant, stem or a few leaves in your fish bag will provide added comfort and shelter for your fish while they wait.
  • Please label each bag clearly with the following details: vendor-lot number, species name, number of fish in the bag (unless it’s just one), and whether the fish are male / female (if known). If you wish, you can also include additional information such as: species origin, an adult photo of the species if your fish is a juvenile (or use a photo of the juvenile’s parents), the generation if known, etc… Be sure your bag labels are clearly visible and easy-to-read. Hint: the more information you can provide to the auctioneers, the more easily they can sell your fish to a suitable home, and for the best possible price.
  • If more than one fish bag is to be sold as a single lot, mark each bag with the vendor-lot number and also mark each bag as being, e.g. “1 of 3”, “2 of 3”, “3 of 3.” Be sure to use tape, a larger bag, etc. to keep all bags within each lot together as one unit so that the individual bags don’t become separated, or get confused with other lots nearby.
  • When transporting your fish to or from the auction, use a foam container or cooler box (e.g. a camping cooler) to keep the air around the bags steady at room temperature. As an inexpensive alternative (though don’t use this method for extended periods of time as it’s a bit less effective), you can also use triple-bagged paper shopping bags (e.g. paper Co-op or Safeway bags) with extra newspaper inside, then and roll up the top to keep any outside cold air out. Whichever method you choose, it is especially important for your fish to be insulated when traveling on winter days.

What’s New In Cyprinid Studies: Part 3


Cyprinids are great ones for schooling; a survival mechanism that evolved as an anti-predator measure (many eyes watching are better than just two), and as a food-finding mechanism (better a small share in the crowd frequently than the occasional big bite by yourself). It is known that cyprinids can recognize each other as individuals, and prefer to school with familiar friends rather than strangers, just as humans prefer to hang out with the old gang. The bigger a school is, the better it is for predator defense and food hunting. A recent study on the minnow Phoxinus phoxinus showed that given a choice between a shoal of friends or a bigger one of strangers, they prefer their friends [3]. However, this preference decreases as the relative size of the school of strangers increases. When the strangers are about twice the size of the friends group, an individual minnow presented with a choice between the two will go with the strangers.

So from a practical point of view for the aquarist, what does all this business about schooling mean? Basically, it suggests that cyprinids are happier in groups rather than solitary fish in a tank. The bigger the group, the better, and probably the more successful you would be at spawning them. This is not to say that you would not be able to spawn a solitary pair, but if you are having problems, it is wise to consider how the fish behave in natural conditions.


Cyprinids are understandably timid fish, as in habitat they are usually more eaten than eater. The schooling mechanism of social behaviour is a common defensive mechanism against predators, since more fish mean more eyes watching more angles of attack.

A group of chemicals known as alarm pheromones are used to alert nearby fish about risks. There is a problem of false alarms, since there are numerous possible stimuli in habitat which might provoke false alarms. Cyprinids therefore not only have to keep an eye out for predators but to decide if an object is worth getting excited about. There are two types of chemicals needed to react to predators. Firstly, the predator leaves an odour in the water, and secondly some experienced fish has to secrete alarm pheromone when it detects the odour. Cyprinids can quickly learn to associate the two chemicals, such that when they smell the predator in the water they will automatically go on full alert [6].

There is also visual detection of predators. A recent study on this aspect used the fathead minnow Pimephales promelas as a test indicator [1]. The experiment showed that motion was used as a more reliable alarm rather than shape. Lots of fish are fish-shaped, but one moving in a purposeful manner with gaping mouth directly to another fish can only spell trouble. Random motion, with fin-flicking, will not likely trigger alarms.

Historically, most aquarists forget or don’t know about pheromones in the water. Humans are visually oriented, and we have one of the poorest abilities to detect scents in the animal kingdom. What may seem to be clear water in a peaceful aquarium could be a stress-inducing soup of pheromones to the cyprinids in a community tank with potential predators. To take a commonly seen example, consider a community tank with angelfish and danios. The angelfish are predators, poor ones perhaps, but predators nonetheless. Small cyprinids can out-swim their attackers, but are unable to get away from them. They thus live in a soup of alarm pheromones and predator odours that stresses them.

It is known that minnows prefer to forage at night to escape attention of predators, but as hunger increases, they are more active during the day [4]. This suggests that if an aquarist is having trouble finding the cyprinids in the tank, skimping on the food will make them more conspicuous. There is a common practice among many aquarists based on this idea. Fish intended for showing at a club exhibition should be starved for a couple of days prior to the show. Hunger increases activity and foraging behaviour, and will also increase the likelihood of impressing the judges. A well-fed fish entered in a show is more likely to laze about with droopy fins not doing much of anything, leaving the judges to pass it over in favour of its neighbour right up front at the glass wagging its body in the hope of food.


Cyprinid courtship usually involves the male displaying bright colours and/or unusual body characteristics such as over-developed finnage. Colours depend on diet, and females proceed on the assumption that a male with bright colours has a better diet and is healthier than a drabber male. However, there is a limit to extravagant ornamentation for sexual selection. If too extreme, it will affect adjacent body tissues or organs [2]. In the aquarium this may not matter so much, but in habitat, a long-finned goldfish would not be able to out-swim a predator. The egg-shaped breeds of goldfish with cramped guts and a waddling gait would quickly be picked off by predators in habitat. What does matter for aquarists is that extreme ornamentation might affect the fish’s physiology, such as bizarre body shapes that produce distorted internal organs with concomitant internal troubles. Among the domesticated cyprinids, the only such suspect fish are goldfish breeds. This is when you see reference to some breeds as being delicate and difficult to keep. The real point is that they manage to stay alive, not that they are difficult to keep.

Just as with other types of aquarium fish such as cichlids, the cyprinids have dominance hierarchies. It has been previously shown that dominant males should be removed from a tank after they’ve spawned a few times in order to allow other males to contribute something to the gene pool. It does matter, however, what condition the smaller, sub-dominant males are in. In Pimephales promelas, small males will advance their spawning when the dominant males are removed, and will produce as many offspring. Such offspring are smaller though, which in habitat is because the small males didn’t have time to get their young plumped up before end of season [5]. In the aquarium, where seasons don’t exist, this effect means that the young will have to be fed heavier and longer to get them up to par. Normally this would not be an important effect in the fish room, but for those aquarists who raise fish in outdoor ponds it might mean smaller juveniles. To summarize from a practical point of view, if you want to get a fresh burst of spawning from your fish, remove the dominant male and be prepared to feed heavily the next batch of fry.


You do weekly partial water changes on your aquariums, right? The filter is also rinsed out in the change bucket at the same time, right? It is not enough to say the aquarium is in good condition because the water is clear. Many problems are invisible, as not all toxins are pigmented or otherwise indicate themselves. Cyprinids tend to be messy fish, and even minnows will raise water turbidity and turn the tank into a phosphate soup if regular water changes are not done [7].


1] Wisenden, B.D., and K.R. Harter (2001) Motion, not shape, facilitates association of predation risk with novel objects by fathead minnows (Pimephales promelas). ETHOLOGY 107:357-364

2] Emlen, D.J. (2001) Costs and the diversification of exaggerated animal structures. SCIENCE 291:1534-1536

3] Barber, I., and H.A. Wright (2001) How strong are familiarity preferences in shoaling fish? ANIMAL BEHAVIOUR 61:975-979

4] Metcalfe, N.B., and G.I. Steele (2001) Changing nutritional status causes a shift in the balance of nocturnal to diurnal activity in European minnows. FUNCTIONAL ECOLOGY 15:304-309

5] Danylchuk, A.J., and W.M. Tonn (2001) Effects of social structure on reproductive activity in male fathead minnows (Pimephales promelas). BEHAVIORAL ECOLOGY 12:482-489

6] Korpi, N.L., and B.D. Wisenden (2001) Learned recognition of novel predator odour by zebra danio, Danio rerio, following time-shifted presentation of alarm cue and predator odours. ENVIRONMENTAL BIOLOGY OF FISHES 61:205-211

7] Zimmer, K.D., M.A. Hanson, and M.G. Butler (2001) Effects of fathead minnow colonization and removal on a prairie wetland ecosystem. ECOSYSTEMS 4:346-357 ?