Uglier Fish Have Better Sperm

If Brad Pitt and Angelina Jolie were guppies instead of people, they may have had to adopt. That’s according to new research reported by the BBC, which has shown that the most attractive male tropical guppies tend to have less competitive sperm.

Popular among aquarium owners because of their vibrant colors, guppies are flamboyant fish which engage in a very peculiar evolutionary drama. Australian researchers have revealed that less attractive male guppies have “better sperm” than their more dashing counterparts, suggesting that, for these fish at least, there is a biological trade off between attractiveness and sperm quality.

While some male guppies invest more heavily in their appearance with the hope of attracting more mates, other male guppies invest in spawning faster swimming sperm. According to Professor Jonathan Evans from the University of Western Australia, who carried out the study, the findings support “sperm competition theory”.

Originally proposed by British biologist Geoffrey Parker, sperm competition theory is defined as the “competition between sperm of two or more males for the fertilization of an ovum.” In the case of guppies, less attractive males who are unable to attract a mate typically try to compensate by performing non-consensual “sneak” matings. They gain an advantage over their flaunty competitors because their sperm is superior.

“Males that predominantly performed sneak matings were less ornamented but had faster swimming sperm than those that predominantly used courtship,” explained Evans. “The reproductive advantage enjoyed by attractive males might potentially be offset by the poor performance of their ejaculates during sperm competition.”

By Bryan Nelson, MNN


K s Goh
KS Goh4 years ago

Thanks for the article.

Sulette Matthee
Sulette Botha5 years ago


Lupe G.
Guadalupe G.5 years ago

It's no surprise; like with humans, the "pretty" ones tend to be higher maintenance with less substance (I'm generalizing based on experience) while the average person is more well-rounded (no pun intended). The less attractive tend to overcompensate to compete with the dating market. There is a song that says that if you want to be happy for the rest of your life ask an ugly girl to marry you (because they will do whatever makes you happy because you chose them). I know it's an exagerration but everything springs up from something...

Deborah C.
Deborah C.5 years ago

Thanks for article.

Beth M.
Beth M.5 years ago

How interesting!

K s Goh
KS Goh5 years ago

Thanks for the article.

Teresa Wlosowicz
Teresa W.5 years ago


Tierney G.
Tierney G.5 years ago

Interesting! these fish have been hybridized to death. Some of the males can barely swim because of excessive finnage. I wonder if they took that into consideration?
The females also have prolapsed uterus problems more often. I am not sure if they call it a uterus in a fish but just to explain.
It is probably because these fish evolved faster than nature would ever have allowed. Back to the basics is best.

Tammy Smith
Tammy Zabel6 years ago

Who thought to "research" this in the first place?

charmaine c.
Charmaine C.6 years ago

Hilarious Megan! Lol!