Drunk Fish Convince Sober Ones to Follow Them Around

By Elizabeth Preston | May 19, 2014 8:53 am

zebrafish

It’s a good thing fish can’t operate a vehicle. Not only do drunk zebrafish swim extra fast, but they somehow get all the sober fish to follow them. Essentially, a drunk fish becomes the designated driver for the whole group.

Although a fish is only marginally like a human, fish can be convenient subjects for scientists who want to study the effects of alcohol. That’s because to get a fish tipsy, you don’t have to force it to drink anything. You only have to put a small concentration of alcohol into its tank.* Maurizio Porfiri, an associate professor at the New York University Polytechnic Institute of Engineering, used this technique to show last year that drunk zebrafish don’t fear robotic predators.

For his latest study of intoxicated fish, Porfiri and his coauthors had their subjects swim in three different alcohol concentrations: 0.25%, 0.5%, and 1%. The highest concentration translates to about a 0.1% blood alcohol content in the fish, Porfiri says—above the legal limit of .08% for people in the United States.

Earlier studies had found that a moderate dose of alcohol makes fish more active, while a higher dose slows them down. But for this study, Porfiri wanted to see how an alcohol-exposed fish would behave when it was surrounded by sober ones.

After letting each zebrafish soak for a while in a beaker of water and ethanol, he dropped it into a tank with four sober zebrafish and watched them interact for five minutes. A camera recorded the group from above so that the scientists could measure the fishes’ movements using a tracking algorithm they’d recently developed.

Alcohol-exposed fish swam faster in a group than they did alone. This might be because moderate intoxication makes them hyperactive, as earlier studies found; they may overreact to the stimulus of seeing other fish nearby. Moderate amounts of alcohol are also known to lower fishes’ inhibitions, making zebrafish more aggressive and less afraid of unfamiliar things (or predators).

Meanwhile, the four sober fish didn’t ignore their intoxicated peer as it zipped around the tank: they followed it.

There are a couple of possible explanations for this, Porfiri says. Maybe something about the drunk fish’s one-on-one interactions with the other fish made the group as a whole move in the same direction. Or maybe the sober fish looked at their non-sober tankmate and saw a leader. “It is likely,” Porfiri says, that the drunk fish’s uninhibited behavior “is perceived as a boldness trait, thus imparting a high social status.” As they followed the drunk fish, the sober ones also sped up to keep pace, swimming roughly a third faster than they would have otherwise.

The very drunkest zebrafish, though, lost their leader status. Fish that had been exposed to the highest alcohol concentration began to lag behind the rest of the group, following instead of steering. Since higher alcohol doses have “sedative effects,” Porfiri says, the drunkest fish slow down and start to display “sluggishness in response to the rest of the group.”

Porfiri isn’t ready to conclude that being buzzed turns humans into better leaders. It’s true that one reason to study alcohol-imbibing zebrafish is to make comparisons to human behavior. But “these similarities exist at a very basic level,” he stresses. “It would take many more studies to draw direct parallels” between ethanol-dunked zebrafish and soused people. Perhaps by then, the fish will have learned how to designate a driver.


*Please don’t kill your fish trying to do this at home. I don’t want little Betta-Zoid’s blood on my hands.

Image: zebrafish by Tohru Murakami (via Flickr)

Ladu F, Butail S, Macrí S, & Porfiri M (2014). Sociality Modulates the Effects of Ethanol in Zebra Fish. Alcoholism, clinical and experimental research PMID: 24819037

  • Joan_Savage

    Do the researchers know if sober zebrafish might follow any zebrafish that is more active?

    • http://blogs.discovermagazine.com Longmire

      The research would definitely justify the drug use of many a politician.

  • http://www.worthynews.com/ Joe DeCaro

    Since fish are only “marginally” like humans, who funds this nonsense?

    • Doug

      I’m thinking…. New York University Polytechnic Institute of Engineering, just like the article references.

      • http://www.worthynews.com/ Joe DeCaro

        NYU is doing the research, if you could call getting fish drunk “research”.

  • http://goodbyemag.com Steve Miller

    This is the kind of headline I wish I could put on my stories

  • A Woman

    Alcohol is a poison to both fish and humans. I hope you don’t expose these fish to other toxins just to speculate about their reactions. Poison=bad

  • Xiang Ji

    Such a farfetched nonsense with an awkward theory. How can you know what the fish are “thinking”? Maybe some more followed the fish because it had a eerie smell, or simply random results. I certainly don’t think we humans tend to follow a drunkard all the day, at least when it comes to important and serious matters. A terribly usupported and misguiding claim.

    • http://blogs.discovermagazine.com Longmire

      People tend to follow courageous individuals, alcohol is known as liquid courage. Drunk people rarely respect the authority of or submit to another hence others follow. Psychology isn’t ideal.

  • Robert Heinz

    2 things –
    1. Fine print is for things that you’d rather people not read.
    2. I feel like it was a bit of a leap to say that the fish saw him as a leader who had “higher social status”. Why wouldn’t you first look back at a natural response that a fish may have. Seeing another fish swimming fast and swimming after it is probably a survival trait more than anything else. With a fish’s limited vision, if you see one of your own running in a certain direction, your instinct is gonna be that he is running from something and that you should follow.

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Inkfish

Like the wily and many-armed cephalopod, Inkfish reaches into the far corners of science news and brings you back surprises (and the occasional sea creature). The ink is virtual but the research is real.

About Elizabeth Preston

Elizabeth Preston is a science writer whose articles have appeared in publications including Slate, Nautilus, and National Geographic. She's also Editor of the children's science magazine Muse, where she frequently writes in the voice of a know-it-all bovine. She lives in Massachusetts. Read more and see her other writing here.

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