A method for the comparison of chromaticity parameters in fish skin: Preliminary results for coloration pattern of red skin Sparidae M. Pavlidis a, ⁎ , N. Papandroulakis b , P. Divanach b a University of Crete, Department of Biology, P.O. Box 2208, GR-71409, Heraklion, Crete, Greece b Hellenic Centre for Marine Research, Institute of Aquaculture, P.O. Box 2214, GR-71003 Heraklion, Crete, Greece Received 20 July 2005; received in revised form 9 May 2006; accepted 12 May 2006 Abstract Skin coloration patterns in fish are of great physiological, behavioural and ecological importance, can be considered as an index of animal welfare in aquaculture and as an important quality factor for the retail value, especially of red skinned fish. In the present study we developed an appropriate method for comparisons of the skin chromaticity parameters in wild (Pagrus pagrus, Pagrus caeruleostictus, and Dentex gibbosus) and farmed red skin Sparidae and investigated the effect of storage time on skin colour of farmed Pagrus pagrus. The three-dimensional characteristics of colour appearance (lightness — L ⁎ , hue — H° ab and chroma — C ab ⁎ ) were calculated. A new index, named Entire Colour Index (ECI ), was developed to express hue and chroma which as combined variables, cannot be considered separately. In all species there was a remarkable dorsoventral gradient in mean L ⁎ and H° ab , with the ventral area being statistically significant brighter than the dorsal one. ECI value was species specific but did not show any statistically significant dorsoventral gradient, with the exception of P. pagrus. Skin melanin and carotenoids content presented differences between the Pagrus and the Dentex species that may explain the differences in the observed chromaticity pattern. Storage time affected lightness and hue only in the dorsal skin area. However, the effect of storage on ice was better reflected in mean ECI value which showed a marked decrease from Day 3 to Day 7 in both the dorsal (Day 0: 8.96 ± 0.40; Day 7: 2.86 ± 0.29) and ventral (Day 0: 8.97 ± 0.18; Day 7: 4.10 ± 0.29) skin area. Our results provide data for a non-subjective determination of skin colour pattern and show that ECI offers a good index of the actual colour in a meaningful and objective way. © 2006 Elsevier B.V. All rights reserved. Keywords: Colour; Dentex; Pagrus; Skin 1. Introduction Fishes display a variety of skin coloration patterns which are of great ecological, physiological and beha- vioural importance. According to Moyle and Cech (1988), eight general colour patterns can be described in fishes: (1) red coloration, (2) poster colours, (3) disruptive coloration, (4) countershading, (5) eye ornamentation, (6) eye spots, (7) lateral stripes, and (8) polychromatism. The sophisti- cated chromatic properties observed in this class of vertebrates provide protection from predators, advertising territories, assist in survivor, and intraspecific communi- cation (Fujii, 1993). In addition, carotenoid pigments, which are responsible for the bright red and yellow hues of red skin porgies, are of prime importance for enhancing vision and provide protection from metabolic oxidation. Skin pigmentation pattern can be considered as an index of animal welfare in aquaculture species and a Aquaculture 258 (2006) 211 – 219 www.elsevier.com/locate/aqua-online ⁎ Corresponding author. Tel.: +30 2810 394084; fax: +30 2810 394408. E-mail address: pavlidis@biology.uoc.gr (M. Pavlidis). 0044-8486/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2006.05.028