Published: 8/9/2016

Smithers has announced new findings regarding the duration of  fish full life-cycle testing. The testing protocol, designed to assess the toxicity of a given chemical over the full life-cycle of fish, historically requires an average exposure of 260 days (or 8.7 months). The Smithers studies produced consistent and accurate data with an exposure of approximately 180 days (6 months).

“Our recent control performance shows that a fathead minnow full life-cycle test can be accomplished during a shorter than traditional timeframe while providing consistent, high reproductive output,” said Ron Biever, Chief Scientific Officer at Smithers and the team of scientists leading the studies. “Decreasing the necessary length of these studies provides our clients with actionable data sooner, helping to protect and enhance their testing investment.”

The fathead minnow (Pimephales promelas) is a common choice for fish life-cycle testing. However, their lifespan is relatively long and reproduction data tends to be highly variable. Therefore, confidence in the evaluation of effects on their reproduction and development during exposures over multiple generations is often limited by variable responses. The traditional test design (Benoit, 1981), typically involves a 260-day exposure, which the Smithers approach improved upon by 80 days.

In order to achieve this, the Smithers Viscient team worked to manage the fathead minnows’ diet at different life stages, to maintain a constant temperature at 25.5 +/- 1.50 C, and to utilize a consistent strain of fathead minnow. All of these factors played an important part in the enhanced maturation rate and fecundity (e.g. >40 egg/female/day over a 6-week period) common to the traditional test design. In addition, with the consistent fecundity numbers, the spawning phase has been condensed from the scope of the original test method.