Exposure to the antidepressant fluoxetine causes shrimp to radically alter their behavior. While normal shrimp are more likely to avoid swimming towards light because it's often associated with prey like birds or fishermen, those exposed to fluoxetine become five times more likely to swim towards light than away from it. That change in behavior places them in harm's way, and if enough shrimp are exposed to the antidepressant the entire population could be at risk.
So much for shrimp cocktail.