Welcome to the World of Fish!
This section of the site covers not just fish though, divided into coldwater, freshwater and marine, but also various aquatic invertebrates, including sea anemones and other typical occupants of a reef aquarium.
Learning to trust fish - your life might depend on it....

As any fishkeeper knows, water quality is vital when it comes to maintaining an aquarium successfully. The behaviour of the fish will alter if they are exposed to pollutants in the water. The US Army Center for Environmental Health Research started research in this area to safeguard drinking supplies back in 2000. The resulting commercial system, known as IAC 1090, having been marketed by the International Automation Corporation, relies on the bluegill (Lepomis macrochirus), a member of the sunfish family Centrarchidae, to act as the monitor.

Eight of these fish are housed individually in specially-designed chambers through which the water passes. There are electrodes in each of the chambers monitoring the breathing of the fish, as well as their heart rate and swimming patterns. These are connected to a computer, and if noticeable changes are detected in six individuals within the group, then an alarm sounds automatically. Immediate water-testing commences and an alert is flashed to key personnel both by email and pager.

The precise cause of any problem will not be revealed until tests on water quality have been completed, but already, this method has worked to prevent toxins from agricultural spillages reaching drinking water. In one case, the fishes' reactions revealed the occurrence of a diesel spillage over two hours before conventional water monitoring methods picked it up. The system has been employed around major cities including San Francisco, Washington DC and New York City, and could also provide a vital safeguard in the event of an environmental terror attack.

Each bluegill only spends three weeks working in this way, before being substituted by another, with young fish being selected. Bluegills are ideally suited to this task, being both very sensitive to changes in water quality and also quite sedentary by nature. Adults of this species can grow up to 16in (41cm) long and may live for up to a decade. They are native to North America, where their range extends from Quebec to northern Mexico, and they have also been introduced to Hawaii. Their popular name stems from the distinctive bluish coloring on the sides of their bodies, which also extends around the gills.