Hippopotamus have lived in Pablo Escobar's personal zoo since the late '80s. After the drug lord was shot dead in 1993, most of the animals were shipped away, but four mammals were left in the pond. Scientists estimate that now there are around 100 hippos living there, making them the largest invasive species on the planet. Photo by PB_Images /Getty Images Article content Scientists want Colombia to cull its “cocaine hippos” that roam the Magdalena river basin, breeding voraciously and causing an increasing menace. Colombia’s marshlands have been home to the giant mammals since they were illegally imported in the late ’80s by the drug lord Pablo Escobar.