Researchers have discovered animals can become drug addicts just like humans.
A team, led by Pavel Horky, a behavioural ecologist from the Czech University of Life Sciences in Prague, wanted to test the theory that drugs found in wastewater could influence the behaviour of fish.
They collected water found in freshwater rivers that contained a level of methamphetamine and chucked it in a tank along with 40 brown trout.
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The fish were in there for eight weeks before being transferred to a clean tank.
Their study, which was published this week, gave the fish the option of progressing through to cleaner water or their meth-filled water. They chose the latter four days after spending time in the freshwater.
This was done to see whether the trout were suffering from meth withdrawal and, judging by their choice to swim in the drug-ridden water, it's clear they wanted to get their fix.
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An extra 40 brown trout were added as a control and they confirmed that no previous exposure to the meth water ensured they stayed well clear of it when given the option.
Interestingly, the meth-affected fish were found to be less active when going through withdrawal and they had traces of the drug in their brain up to 10 days after their initial exposure.
Dr Horky told CNN: "Fish are sensitive to adverse effects of many neurologically active drugs from alcohol to cocaine and can develop drug addiction related to the dopamine reward pathway in a similar manner as humans.
"Such effects could change the functioning of whole ecosystems as adverse consequences are of relevance at the individual as well as population levels."
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The researchers are concerned wastewater treatment plants regularly dish out this type of drug-filled water into nature. This could cause brown trout and other fish to relocate to these facilities and make them seek out drugs instead of finding food or mating.
If this is realised then it could upend the entire ecosystem and do untold damage.
"Current research from teams around the world undoubtedly shows their adverse impact on ecosystems, which in turn can influence humans," Dr Horky added.
He confirmed all 40 trout affected by the meth water in the study were euthanised and their brain tissues were analysed.
Featured Image Credit: Pavel Horky