3 min read

Regulating Murder

Written by Russell McAndrews

Cichlids are territorial to one degree or another.  Not all are murderous psychopaths, but all are creatures of habit.  For the most part, cichlid behavior patterns are a combination of stimuli and reactions.  When these fish interact socially, the reaction of one fish becomes the stimulus of another.  This is not to say that cichlid behavior is simple, understanding this behavior is complicated by the immense diversity of cichlid species and the relative intelligence of Cichlidae which further complicates behavior patterns by increasing the number of reactions or choices to specific stimuli.  Even among fish of a given breeding behavior such as substratum spawners, many, many variables exist.  Size, for one can play an important role, the larger the fish, the larger the territory required.  This is where hours of fish-watching pay off for the seasoned hobbyist.  The best way to learn is to watch.  In nature, females’ territories will overlap those of males’, in the aquarium, the female must be provided a place of refuge away from any conspecific males.  A territorial male views trespassers either of two ways, wanted and unwanted.  Any fish entering the male’s territory stimulates a reaction in the male who threatens the trespasser.  This will in turn stimulate one of four reactions in the trespasser.  Firstly, a male that for whatever reason does not wish to challenge will retreat.  Secondly, a male which does wish to challenge will return the threat display.  In many species, this will lead to circling and then a fight.  The third possible reaction can be seen from a female in spawning condition; she will refuse to be intimidated and will display in return but will not threaten.  This, in turn, stimulates the male to show off his nest and himself.  The final case is that of an unconditioned female, when threatened, she should retreat.  In the confines of an aquarium, she cannot often leave.  The male’s may pursue and attempt to lure the female back to the nest by displaying.  The amount of patience and perseverance of the male at this point will determine the female’s future as she has just been re-categorized as unwanted.  The case given above is a simplified, generalization and is only meant to help the reader grasp the pattern of stimulus and reaction.

One behavioral oddity which I have witnessed is the “behavioral lock-up”.  This occurs when one fish never receives the proper stimulus to get itself out of a situation that it has gotten itself into.  For instance, a male of a spawning pair for an unknown reason eats some of his own progeny.  This stimulates the female to defend her brood; she attacks the larger male driving him away and causing him severe damage and/or killing him.  Why doesn’t the male defend himself?  Even though he may be the larger fish, the male loses the fight.  Actually, a fight never takes place because the male never defends himself.  The female receives a stimulus to attack the male but the male does not receive a stimulus to attack the female even though she is attacking him, this is what I call “behavioral lock-up”.

Some cichlids are extremely social and all establish a hierarchy or pecking order among their ranks.  The genus Tropheus is a good example of a highly gregarious group of fishes.  In captivity, Tropheus set up an elaborate, rigid, social structure, which enables them to co-exist in situations of dense population.  An individual fish, which has been removed from this structure, even for thirty minutes, would probably be murdered when reintroduced if precautions are not taken to totally disrupt the existing hierarchy.  Territorial boundaries and pecking orders might not be that obvious to the hobbyist, but to the aquarium inhabitants they are life and death.

Whenever adding or subtracting fish, keep in mind that they are members of a society.  A rule of thumb I follow when adding a new member to a community is to rearrange the rockwork of décor thoroughly to ensure the disruption of all existing territories and confuse the inhabitants.  This puts the newcomer on an equal footing with the rest of the community before pecking orders and territories have had a chance to reform.  It is also recommended to keep an eye on the newcomer for an hour or so.  If another fish is going to take a special dislike to the newcomer, it will generally happen right away.  Distract the inhabitants by feeding the tank at the same time.