A new study by scientists from the University of Frankfurt found the Shortfin molly – a popular fish for tropical aquariums – places a premium on sexual activity. Therefore a male engaging in homosexual behaviour can impress a female with his virility and fitness.
“Sexual activity in itself is a sign of quality for females because sick or underfed males show little sexual behaviour,” said evolutionary biologist David Bierbach, adding this could possibly explain bisexuality in some other species as well.
Publishing their findings in the British journal “Biology Letters,” the researchers picked the Shortfin molly because unlike many fish, insemination takes places inside the female, which bears its young live.
Known by the scientific name Poecilia mexicana, the fish found in rivers in Central and South America normally grow between four and six centimetres long. Whereas the males have orange-turquoise markings, the females are a more subdued beige.
The scientists showed a Shortfin molly female videos of a male engaging in either heterosexual or homosexual behaviour. “Both turned the female on,” said Bierbach.
The females also spent more time watching the fish pornos rather than videos of males not engaging in any kind of sex.