Native people in the Amazon rainforest use a toxin to help them catfish the toxin interferes with the gas exchange in the fish which makes them slow and easy to catch?

Barbasco plant.

Explanation:

Native people in the Amazon rainforest use a toxin extracted from Barbasco plant roots which is responsible to stun fish and make it slow to catch the fish easily. This method is used only on the small streams not on large river. This toxin helps in the slowing of the catfish which can't be catch without of this toxin because catfish is very active and quick which is hard to catch at this state so that's why the Native people in the Amazon rainforest use this toxin.