Community Research and Development Information Service - CORDIS

Husbandry conditions and skin colour

The role of husbandry conditions in skin colour was investigated, and in particular the effect of background colour, lighting spectrum, light intensity and stocking density.

This study shows that:
- Background, lighting spectrum, light intensity and stocking density have an important effect on skin chromaticity parameters. White background increases skin brightness in levels similar to that of wild fish but reduces skin chroma. Blue lighting spectrum increases skin brightness in dark background (black and red) held fish but did not show any significant effect on hue or chroma. Low light intensity resulted also in higher L in fish held under dark backgrounds. However, fish placed in complete darkness show a decreased L value. Stocking density affected significantly L, Hue and ECI. In particular, fish held under dark backgrounds and high stocking density showed lower L and ECI values than fish held at low stocking density.

- There was no effect of background, lighting spectra, light intensity and stocking density on the number of melanophores per mm² of skin.

- Higher skin melanin content was observed in red porgies held under dark backgrounds, high light intensity and high stocking density compared to fish held under low light intensity and low stocking density.

- The results altogether indicate that the observed differences in skin lightness are related to differences in the motility of skin chromatophores; melanophores in pale fish are aggregated while in control fish dispersed. Concerning the neuroendocrine regulation of this motility, melanophore aggregation is not mediated through circulating cortisol or MSH, but through changes in plasma catecholamines.

Reported by

University of Crete
GR - 714 09 Heraklion
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