London, Aug 30 (IANS): Native to southern Africa, Mozambican tilapia fish use urine to reduce aggressive behaviour in other males, lure females to the nests that they make and stimulate spawning, says a study.

Researchers have identified that the urine of the male tilapia fish contains pheromones (a chemical substance produced and released into the environment by an animal), that boosts hormone production and accelerates egg cell maturation in reproductive females.

Thus, the pheromones help to synchronise female spawning and external fertilisation by males and so as to increase the odds of reproductive success.

Dominant males have been observed to urinate more often and squirt larger quantities of urine in water during fights compared to their subordinate rivals.

For the study, Tina Keller-Costa and her colleagues from the University of Algarve in Portugal collected urine samples from dominant males and purified the samples in several steps, testing them for biological activity as pheromones after each step.

This procedure resulted in two pure substances whose chemical structures were elucidated using nuclear magnetic resonance spectroscopy (NMR).

"The two structures are stereoisomers or mirror images of a steroid linked to glucuronic acid," said Bernd Schneider, head of the NMR lab in Germany.

Both males and females showed highly sensitive responses to the odour of these two steroids.

The study appeared in the journal Current Biology.