New research claims that fish can become addicted to methamphetamine after ingesting it through contaminated water.

The study, led by Pavel Horky, a behavioral ecologist from the Czech University of Life Sciences in Prague, involved 40 brown trout being placed in a tank of water containing a level of methamphetamine that was previously found in freshwater rivers.

Another 40 fish were used as a control group.

After eight weeks, the researchers moved the fish that were inside the methamphetamine-laced tank to a new one filled with clean water.

The fish were then tested for addiction every other day. Researchers also offered the fish the chance to go into water containing the drug or water without.

The study found that the trout that had spent the eight weeks in the water with methamphetamine chose the water containing the drug in the four days after moving to the tank with clean water.

Researchers say this shows the animals were going through withdrawals because they chose the drug when it became available.

They also found that the fish who were addicted to the drug were less active than those who hadn’t come into contact with it.

According to the study, drugs end up in water supplies after being excreted from users and are expelled through wastewater treatment plants, which aren’t set up to deal with these types of contaminants.

Speaking to CNN, Horky said, “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.”

He also said that such a drug addiction could prompt fish to spend more time around water treatment areas, which can be harmful to fish, in an attempt to get another hit of the substance.

“Such effects could change the functioning of whole ecosystems as adverse consequences are of relevance at the individual as well as population levels,” he added.

The researchers suggest these addictions could interfere with natural processes, such as mating and foraging.

The study is yet another example of how human behavior is having a negative impact on wildlife.

Horky told CNN, “Current research from teams around the world undoubtedly shows their adverse impact on ecosystems, which in turn can influence humans.”