Fishy sensor

Researchers at Purdue University have harnessed the sensitivity of days-old fish embryos to create a system capable of detecting a range of harmful chemicals.

By measuring rates of oxygen use in developing fish, which are sensitive to contaminants and stressful conditions, their system could reveal the presence of minute levels of toxic substances before they cause harm.

Marshall Porterfield, an associate professor of agricultural and biological engineering at the university, said: 'It could be used as an early warning system against environmental contamination or even biological weapons.'

Respiration is often the first of a fish's bodily functions affected by contaminants. The Purdue system uses a fibre optic probe to monitor this activity and produce results within minutes.

In the laboratory, Porterfield and his researchers first manually positioned the tiny optical electrode just outside individual embryos of two-day-old fathead minnows. At 1.5mm in diameter, they were slightly smaller than the head of a pin.