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Aquatic Sciences

, Volume 66, Issue 2, pp 239–245 | Cite as

Humic substances affect physiological condition and sex ratio of swordtail (Xiphophorus helleri Heckel)

  • Thomas Meinelt
  • Kurt Schreckenbach
  • Klaus Knopf
  • Andreas Wienke
  • Angelika Stüber
  • Christian E. W. Steinberg
Research Article

Abstract.

Exposure of young swordtail (Xiphophorus helleri) to increasing concentrations of synthetic humic substances (HS1500) significantly effected the physiological condition and slightly effected the sex ratio of the fish. Any exposure enhanced the body mass development of the swordtail compared to the control. No dose-dependent effect of HS on growth was detectable. After a two-week period of stressful handling, the HS-exposed fish recovered quickly whereas growth stagnated in the control fish. The examination of gills, fins, and skins revealed no infestation with ectoparasites. We assume that the growth promoting effect of HS1500 was due to an overall stimulation in metabolism. Furthermore, the sex ratio of fish exposed to HS1500 for 21 weeks slightly shifted in favor of females in a dose-dependent manner. Although the mode of action is still obscure, there is a probability that alkylphenol structures in HS1500 may be responsible for this weak feminization.

Key words.

Humic substances fish growth fish condition sex ratio feminization. 

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Copyright information

© EAWAG 2004

Authors and Affiliations

  • Thomas Meinelt
    • 1
  • Kurt Schreckenbach
    • 2
  • Klaus Knopf
    • 1
  • Andreas Wienke
    • 3
  • Angelika Stüber
    • 1
  • Christian E. W. Steinberg
    • 1
  1. 1.Leibniz-Institut of Freshwater Ecology and Inland FisheriesBerlinGermany
  2. 2.Institute of Inland FisheriesPotsdam-SacrowGroß GlienickeGermany
  3. 3.Max Planck Institute for Demographic ResearchRostockGermany

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