Thursday, 12 October 2017

Do male fish prefer them big and colourful?

October 10, 2017

Male black-finned goodeid or mexcalpique fish know what they want when they pick a female to mate with; they prefer them big-bellied and as orange as possible. Interestingly, females displaying these traits are the ones most able to produce more offspring that survive, two researchers from the National Autonomous University of Mexico have found. The study by Marcela Méndez-Janovitz and Constantino Macías Garcia is published in Springer's journal Behavioral Ecology and Sociobiology.

The black-finned goodeid (Girardinichthys viviparus) from Mexico is a very promiscuous species of fish, with males constantly seeking a suitable partner to mate with. The females are only sexually receptive for a few days every two months after giving birth. The black-finned goodeid is viviparous, meaning that young fish fully develop inside the female's body before they are born.

During courtship, males concentrate all their attention on only one female at a time. The wooing process is made even harder because females can be quite selective. Courtship consists of three basic elements, and is initiated when the male approaches the female he has chosen. His interest is signalled through his dorsal and anal fins standing erect. He then folds these fins over the female's body, in a type of embrace, before starting to swim in synchrony with her. The male will go on to occasionally attempt to grip the female more firmly and to copulate.


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