In the Camino Verde trial brigadistas and other community members gather larva-eating fish from rivers and streams (see photo) and distribute them to households to put them in water containers as a substitute for temephos. The practice has spread as a result of meetings among brigadistas from different neighborhoods.To encourage the use of this ecological resource brigadistas demonstrate to householders how the fish eat the larvas and they explain that the fish do not need any other special food because, even in containers that have no larvas, the water contains micronutrients sufficient to keep them alive.

Brigadistas and other residents have begun to diversify this practice in different ways. In one urban community of Acapulco they are putting fish into water congtainers found in abandoned houses. In a suburban community of Acapulco where there are several plant nurseries they have convinced the owners to put fish into water that sustains aquatic plants. Some Costa Grande and Costa Chica communities are using not only fish but also crayfish and shrimp. People can see that this tactic works because they now know how to look for larvas and can see that there are none. Residents generally prefer having fish rather than temephos in their water receptacles. We have noticed that biological control works best in rural settlements where the local water supply is not chlorinated.