In the book,The Cichlid Fishes, nature grand experiment in evolution, it is perceived an act that indicates conflict, an act of pre-fighting, or spawning.
the cichlid "it passes deep sideways undulations down its body while breaking with its pectral fins to resist the foreword force; this behaviour is called tail-beating, and may be done in a snap-whip fashion.
The result is an imposing display and one that washes the opponent with a hefty flow of water that may be perceived as sound".
In the act of spawning it may be used to access the suitability of a mate.
"All of this behaviour indicates conflict.
Each fish has positioned itself so that is prepared either to flee or attack.
Fleeing would be done by means of powerful body undulations in which the tail swings from side to side.
Thus tail-beating reflects the urge to escape from dangerous opponent.
At the same time, the fish extends its pectoral finish a breaking action that counters the undulations, reflecting the motivation to stay put and attack the opponent."
in this act they are unconventionally cooperating
"they would be supplying and obtaining valuable information about their opponent while minimizing the possibility of incurring costly injury."
