New Delhi: In an alarming study from the Czech Republic, scientists have found that freshwater fish are becoming addicted to methamphetamine due to the accumulation of the illegal drug in water bodies.
Apart from oil spills and plastic pollution, many of the drugs that humans consume end up in water bodies as effluent treatment is currently not equipped to deal with them.
Previous research has shown that drugs such as fluoxetine, also known as Prozac, in water can embolden fish and alter their behaviour.
However, a new study, published in the Journal of Experimental Biology shows that apart from prescribed medication, illegal drugs like methamphetamine (meth) can also accumulate in waterways.
“Whether illicit drugs alter fish behaviour at levels increasingly observed in surface water bodies was unclear,” said Pavel Horký from the Czech University of Life Sciences Prague.
To study this, the team, including researchers from the University of Southern Bohemia, decided to investigate whether brown trout (Salmo trutta) are at risk of addiction from illegal methamphetamine in their waterways.
How fish are getting addicted to meth
The brown trout were isolated in a tank of water laced with methamphetamine for a period of eight weeks. The water contained a concentration of 1 microgram meth for every 1,000 litres — a level that has been found in freshwater rivers.
The team then transferred the fish to a freshwater tank and offered them a choice between freshwater or water containing methamphetamine, every alternate day for 10 days.
In the event of an addiction, the fish will feel effects of withdrawal and would seek the drug when it was available, the team said.
Tracking the fish’s choices, it became clear that the trout that had spent two months in the methamphetamine-contaminated water had become addicted to it and selected the water containing the drug because they suffered withdrawal in the first four days after moving to freshwater.
The addicted fish were also less active than trout that had never experienced the drug. The researchers also found evidence of the drug in the fish’s brains up to 10 days after the methamphetamine was withdrawn.
Even low levels of illicit drugs in waterways can affect the animals that reside there, the team warned.
The researchers said that the drug addiction could drive fish to congregate near unhealthy water treatment discharges in search of a fix, as well as disturbing their natural tempo of life.
Such evidence of drug addiction in wild fish is another example of unexpected pressure on species living in urban environments, said Horky.