African Cichlids - How do they Communicate? - II
by George J. Reclos
Predators also use their colors to catch their pray. While most of them have the pale colors discussed earlier, some of them try to stay invisible (thanks to their color pattern) and motionless (ambush predators of the Nimbochromis family). A specific species (Nimbochromis livingstoni – also called “the sleeper”) will go one step further. It will lie on its side, eliminate all hues of blue (the male) and change the intensity of its blotches, looking exactly like a dead fish. When small fish come to eat the carcass, they become its pray. This can also be seen in your tanks, provided the correct aquascape and size are chosen.
A Nimbochromis livingstoni in ambush. Some fry is hiding in the nearby rock. After a week there were no surviving fry.
Breeding is also very important for every species and cichlids are no exception. You may be surprised to know that in the wild, the female will actually select which male it will spawn with, which means that color patterns (the mate-recognition signal) play a very important role in this case. Females will not just spawn with the biggest male around. Usually they will choose to spawn with the most “typical” male and this makes sense. Thus, male signals that match female perception are easier to detect and should be preferred by females. Over evolution time this may finally lead to female preference2.
Here starts a very interesting issue. Females will recognize the male signals and will preferably mate with the most “typical” partner. This is good and works perfectly well in the wild and this is the reason we can see different variants / color morphs of cichlids at such a short distance between them. The effect of the environment on the female perception has already been studied and it is shown that there is a direct link between the two3,4,5. Simply put, the environmental conditions in point A (murky water, light colored sand or rocks, presence of green plants etc.), make the color B more evident and better recognizable by the females so after a long period of evolution time, only females preferring color B live in point A and of course breed with males which have color B. In this situation a new color morph will soon prevail6. Any male with another color morph will never be preferred by those females which will always look for the right color signal. Thus, the “different” male will be reproductively isolated.
When a pair from this habitat is added in our tank things will follow the normal breeding procedures sooner or later. However, if a second color morph of the same species is also present in the same tank, things become more complicated. The reason is again, the visual signals. What was more evident in the natural habitat of color morph A is not in our tank. We don’t have murky water, our sand is cleaned every other week, there is a different type of lighting both in color and intensity so the female may just see two males with the same shape and size, the same melanin pattern and more or less the same colors. It is then when hybridization takes place. Things are even worse when we place in our tank a male and a female from different color morphs without their “preferred” mate. In this situation, the female will become less and less discriminating and finally give in5,7. On top of that, the fact that species which normally inhabit vast territories in the wild are forced to live in some square meters (at most !) may force species to hybridize with different species even if their own female is in the same tank5.
The importance of the color signal in cichlid breeding can’t be overemphasized. A recent work has gone that far as to suggest that the reason for the extinction of many cichlids species from Lake Victoria is not due to the introduction of the Nile perch but due to the murky water – a consequence of human activity and the algae bloom8. Under those conditions it is assumed that female cichlids can’t see the bright colors of the males and therefore do not spawn with them. Although this finding has been disputed by others (who claim that it is quite difficult to miss the color when you are 4 inches away) still this shows the importance of color (and vision in general) for the communication between cichlids.
We can observe the cichlids we keep in our tanks and see the way they communicate. Most of us have seen the breeding process of our fishes as well as the “colorless” (female – like) version of subdominant males. I have a tank with more than 30 Cynotilapia “mbamba” in which only one male has the adult coloration. There are about 20 other males with the dull female coloration, a signal of “accepting” the dominance of that male. They may show their true male coloration when fighting between them but they will hide it immediately when the dominant male comes close. I have never seen a female accepting a mating signal by any of the subordinate males. In contrast, they will always breed with the dominant male. This is even more profound in species which have a clear sexual dichromatism. In this case, submissive males will try to keep the female coloration for as long as possible. It is not rare to see males almost fully grown to have an intermediate color or (whenever applicable) the female bars (Melanochromis auratus & Melanochromis chipokae are classic examples). This makes sexing them by their color a difficult task and venting should be used instead.
Cynotilapia “mbamba” dominant male
Two more males in the same tank. The one in the front, clearly bigger shows a low intensity male coloration to the smaller male in the back. However, both will shed the blue bars when the dominant male comes closer.
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