Here's What Happens When Fish Get Drunk

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Let it be known: Humans are not the only ones whose egos are bolstered by booze. A recent study suggests the humble zebrafish becomes a more confident leader when intoxicated.

How does one get a zebrafish drunk, you ask? A team of researchers led by Maurizio Porfiri, associate professor of mechanical and aerospace engineering and director of the NYU Polytechnic School of Engineering’s Dynamical Systems Laboratory, did so by letting them swim in a solution of ethanol. The solution ranged in alcohol concentration (0.00, 0.25, 0.50, and 1.00 percent ethanol) and some fish got stronger solutions than others. After a fish marinated in the sauce for five minutes, researchers dropped it into fresh water with a school of sober fish and monitored their response to their boozed up buddy.

The results showed that, much like humans, when zebrafish have a slight buzz (those exposed to the .25 percent and .50 percent ethanol concentration), they throw their inhibitions out the window. They swim faster, and show little fear or hesitation. And when they’re around their peers, they go even faster—and surprisingly, the sober fish increase their speed to keep up.

The tipsy fish also showed signs of leadership; its assertive movements steered the direction of the entire group. When the intoxicated fish turned, so did the others. Researchers think this may be because they were influenced by the fish’s alcohol-induced boldness, which they might have interpreted as a sign of leadership.

But, as with humans, it pays to know your limits. Fish exposed to the 1.00 percent ethanol solution lost their leadership skills and lagged behind the other fish, seemingly a bit stumbly and slow. Researchers hope the study can lead to future revelations about how the behaviors of one drunken individual influence an entire group.

But why are scientists getting fish wasted in the first place? It turns out, we’ve been doing it for a while.

Zebrafish, specifically, have a lot of similarities to humans when it comes to development, behavior, and genetics, says Sachit Butail, coauthor of the new paper. And of course, alcoholism and the impacts of drinking on humans are incredibly relevant to modern society. We’ve been studying how alcohol affects zebrafish embryos for years. In 2011, researchers exposed embryos to small amounts of alcohol and found it caused them to be more anti-social as adults. This could lead to new insights into how a pregnant woman’s alcohol consumption impacts unborn babies.

Just last year, researchers—including some also behind the new study—got zebrafish drunk before dropping a robotic decoy fish, designed to look like and act like a fertile female, into their tank. Sober fish eagerly welcomed the new robotic companion. But when under the influence, they avoided it.

But the real question here is this: Do fish get hangovers? Sachit said he couldn’t speculate, but that “they get back to complete normalcy after a day or so.” I guess they really aren’t so different from us.