Colouring
ornamental fish (Cyprinus carpio and Carassius auratus) with
microalgal biomass
L. Gouveia, P. Rema, O. Pereira, J.
Empis-2003
Aquaculture
Nutrition, 9(2):
123
Abstract:
Koi carp and goldfish value increases with
intensity of skin colour, which is an important quality criterion. Fish
cannot fully synthesize their own carotenoid colourings and these must
therefore be included in their diet. Two trials were undertaken to
investigate skin colour enhancement in ornamental species (i.e. three
chromatic varieties of koi carp (Cyprinus carpio), namely Kawari
(red), Showa (black and red) and Bekko (black and white) and
goldfish (Carassius auratus)) by feeding a dietary carotenoid
supplement of freshwater microalgal biomass [Chlorella vulgaris, Haematococcus
pluvialis, and also the cyanobacterium Arthrospira maxima (Spirulina)],
using a diet containing synthetic astaxanthin and a control diet with no
colouring added for comparison. In the first trial, five homogeneous
duplicate groups of 25 juvenile koi carp (C. carpio) (initial mean
body weight 24.6 ± 0.7 g) were fed, for 10 weeks, one
of the four diets containing 80 mg colouring/kg diet. In the second
trial, this procedure was repeated for five homogeneous duplicate groups of
25 goldfish (C. auratus) (initial mean body weight of 0.9 ± 0.1 g).
Initial and final samples of skin along the dorsal fin were withdrawn, from
five fish per group, for subsequent analysis of total carotenoid content
(spectrophotometric analysis), and red hue (colorimetric analysis, CIE
(1976) L* a* b* colour system). Growth and feed
efficiency were not significantly different between groups administered by
the various dietary treatments. In both trials, dietary carotenoid
supplementation increased total skin carotenoid content. The more efficient
colouring for koi carps was found to be C. vulgaris biomass,
providing both maximum total carotenoid deposition and red hue for the three
chromatic koi carp varieties studied, and particularly for the kawari
variety. For goldfish the best colouring obtained, as ascertained by total
carotenoid content, was also achieved using C. vulgaris biomass, and
red hue was maximum when using H. pluvialis biomass.
(Instituto
Nacional de Engenharia e Tecnologia Industrial, INETI, DER. Estrada
do Paço do Lumiar, Edifício G, Lisboa, Portugal)