Prozac doesn't make fish happy

b3b3853e-8acd-4466-85d9-3ddcef9e3bb1

Editor's Picks
Features Post
The brightest pupils
04 October 2021
Features Post
Dealing with egg ‘fungus’
04 October 2021
Features Post
Rathbun’s tetra in the wild
13 September 2021
Fishkeeping News Post
Report: 2021 BKKS National Koi Show results
13 September 2021
Features Post
The World's forgotten fishes
16 August 2021


The popular antidepressant Prozac may make some people happy, but not male goldfish, according to research to be published by Canadian scientists in an upcoming issue of the journal Aquatic Toxicology.

The study by Jan Mennigen and coauthors examined the effects of exposure of waterborne fluoxetine (the active ingredient in Prozac) on the reproductive physiology of male goldfish. 

The authors exposed male goldfish to differing concentrations of fluoxetine, representing the highest concentration reported from treated waste water (0.54 g/l), and a concentration 100 times greater (54 g/l) before assessing them for various reproductive traits, such as gonadosomatic index, milt volume, and blood levels of the sex steroids testosterone and estradiol.

The authors found that 14 days of exposure to fluoxetine significantly disrupted the reproductive physiology of male goldfish.

Under normal conditions, the male goldfish respond to pheromones released by female goldfish when they are ready to mate by releasing milt (sperm), but the authors found that fluoxetine-exposed male goldfish were responded to the female pheromones by releasing significantly less milt (sperm production is correlated to the level of testosterone in the blood, and the reduction in testosterone level upon exposure to fluoxetine may have played a role in this phenomenon).

Vance Trudeau said: "…we must now consider Prozac-like pharmaceutical products as environmental pollutants that cause sexual dysfunction in fish", noting that the drug has been found in sewage effluents in places where it has been sold.

For more information, see the paper: Mennigen, JA, WE Lado, JM Zamora, P Duarte-Guterman, VS Langlois, CD Metcalfe, JP Chang, TW Moon and VL Trudeau (2010) Waterborne fluoxetine disrupts the reproductive axis in sexually mature male goldfish, Carassius auratus. Aquatic Toxicology doi:10.1016/j.aquatox.2010.08.016