Iron Fertilization Can Enhance the Mass Production of Copepod, Pseudodiaptomus annandalei, for Fish Aquaculture

Copepods are proven nutritious food sources for the mariculture/larviculture industry, however, unreliable methods for mass production of copepods are a major bottleneck. In this study, we modified a previously reported inorganic fertilization method (N: 700 mu g L-1 and P: 100 mu g L-1) by the addition of iron (Fe: 10 mu g L-1, using FeSO4 center dot 7H(2)O) (+Fe treatment) and compared its suitability for copepod culture (Pseudodiaptomus annandalei) to the original method (control). The experiment was conducted outdoors in 1000 L tanks for 15 days. The addition of iron prolonged the growth phase of the phytoplankton and resulted in the production of significantly more small phytoplankton (0.45-20 mu m, average 2.01 +/- 0.52 vs. 9.03 +/- 4.17 mu g L-1 in control and +Fe, respectively) and adult copepods (control: 195 +/- 35, +Fe: 431 +/- 109 ind L-1), whereas copepodid-stage was similar between treatments (control: 511 +/- 107 vs. +Fe: 502 +/- 68 ind L-1). Although adding iron increased the cost of production by 23% compared to the control, the estimated net profit was 97% greater. We concluded that inorganic fertilization, with the addition of iron (Fe: 10 mu g L-1), could be an effective method for the mass production of copepods for larviculture.

Automated summary

In this study, a modified inorganic fertilization method with the addition of iron was found to be effective for the mass production of copepods for larviculture. The addition of iron prolonged the growth phase of phytoplankton and resulted in increased production of small phytoplankton and adult copepods. Although the cost of production was increased, the estimated net profit was significantly greater.