A new approach for the laboratory culture of the fathead minnow, Pimephales promelas

Abstract

Fathead minnows are routinely cultured for use in aquatic toxicology studies. A new mass culture system described in the present study consisted of 6 stainless steel tanks, each containing 68 fish and 20 spawning substrates. Spawning results are compared with a previous system of 22 individual glass aquaria, which contained 16 fish and 4 spawning substrates per tank. During a 19-mo period, the new system produced an average of 4105 eggs/d, compared with an average of 2465 eggs/d with the previous system. Labor and maintenance were reduced with the new system. The stainless steel tanks eliminated aquaria glass breakage, and daily water use was reduced by 45%. Analysis of reference toxicant data from fish cultured using both systems indicated no change in the sensitivity of the test animals. Analyses of 2009 egg production data determined that a 6:1 to 7:1 female to male ratio had a significantly positive impact on egg production levels and that 6-mo-old breeding stock should be introduced to the spawning tanks in mid-spring for optimal egg production during the rest of the year. Implementing a stainless steel mass culture system significantly increased efficiency of egg production; reduced turnaround delay of mature animal availability for toxicity and molecular testing; and reduced labor time, costs, and inherent safety hazards, compared with glass aquaria systems.

Fathead minnow reproduction: Implications for commercial culture

“…Once test fish reached maturity, spawning was initially intermittent and only increased as of Days 254 and 256 in the two trials. The trials started in October and December, thus this increase in egg production occurred in April to May, corresponding to the time of natural reproduction and possibly reflecting seasonality in fecundity in the laboratory, as seen by Gordon et al (). Direct comparison of fecundity data from Thurston et al () with other studies is not possible, as reported fecundity was based on total egg production divided by the total age of each female, rather than spawning duration.…”

“…The standard protocol for evaluating the effects of potential toxins on the reproduction of fathead minnows called for a 2:1 sex ratio, with four females to two males per replicate tank (Ankley, Jensen, Kahl, Korte, & Makynen, ). In large tanks with 68 fish, a ratio of 8 males to 60 females optimized egg production (Gordon et al, ). Roush et al () considered that the best sex ratio to produce even‐aged fathead minnow embryos for testing purposes was four females to one male.…”

“…Fathead minnows are raised for toxicology studies and testing by the private and public sectors. Detailed descriptions of laboratory culture methods for fathead minnows were provided by Denny (), Klemm et al (), United States Environmental Protection Agency (), and Gordon et al (). To ensure comparable results from studies using eggs and fish produced at multiple laboratories, culture protocols are comprehensive and relatively uniform.…”

“…One advantage of paired spawning is that the fecundity of individual females can be tracked, but obviously the sex ratio is fixed at one female per male. In group spawning, a sex ratio of seven females per male was found to be optimal (Gordon et al, ). Gordon et al () described the advantages of a mass culture system using stainless steel tanks (each tank containing 68 fish/135 L) over a traditional system of multiple glass aquaria (each with 16 fish/76 L).…”

“…In group spawning, a sex ratio of seven females per male was found to be optimal (Gordon et al, ). Gordon et al () described the advantages of a mass culture system using stainless steel tanks (each tank containing 68 fish/135 L) over a traditional system of multiple glass aquaria (each with 16 fish/76 L). Spawning tiles with eggs are removed daily and placed in white plastic dishpans for incubation, or eggs are removed and hatched in a separatory funnel or incubation cup (United States Environmental Protection Agency, ).…”