They are also monitors of their surroundings. When ocean and freshwater animals suffer diseases, often something has gone wrong in their environment. Aquatic species can be used to study exposure to chemical, biological or physical agents. The common home aquarium zebrafish has proved to be excellent for these tests. Other species that have been used include the horseshoe crab, flounder, killifish, and bivalves like oysters and clams.
Aquatic animals are often less expensive.
They can sometimes provide results more quickly. And they have features such as gill-breathing that allows exposure to respiratory agents through a liquid medium, permitting these exposures to be measured much more accurately. And, since many aquatic animals are a food source for people, studying them gives ongoing information on the safety of the food supply. As the oceans are vast, so are the scientific horizons for scientists who study ocean and freshwater species. Researchers at the University of Wisconsin, Milwaukee, have developed a novel drug that removes lead from minnows, suggesting promise for treating children with lead poisoning.