Nicaraguan authorities began a pilot program in some of the country's central areas to raise tilapia, an exotic fish of African origins, but ecologists warn that its presence in lakes and rivers could have harmful effects. The fish was introduced in Latin America due to its ability to adapt to tropical areas and its rapid reproduction rate.

Salvador Montenegro, of the Aquatic Resources Research Center, told Tierramérica that the tilapia is “is like a small mole, but cancerous. Introducing into the big lakes like the Cocibolca poses a threat because it feeds on animal remains, kitchen waste and animal manure. It produces great quantities of excrement, polluting the water.”

Local environmentalists recommend raising the fish in separate ponds. The tilapia is already part of the local diet and is even an export. In 2000, revenues from international sales of the fish provided Nicaragua 207,000 dollars, but the next year the total fell to 64,000 dollars