This study evaluated the effects of dietary supplementation with four pigment sources on the coloration of
Japanese ornamental carp ( Showa koi) ( Cyprinus carpio L.). Showa koi (which are colored bla ck with scat-tered red patches and white spots) initially weighing 18.04 ± 0.92 g were fed fi ve dietary treatments in
triplicate: a control diet with no added pigments, a diet with 1.5 g kg − 1
Carophyll® red (synthetic, CR
diet), a diet with 200 g kg − 1
we t weight of a photosynthetic bacterium ( Rhodopseudanonas palustris ,PB
diet), a die t with 200 g kg − 1
we t weight of effective microorganisms (EM diet) and a diet with
75 g kg − 1
dry weight feed-grade Spirulina platensis (SP diet). After a 99 day feeding trial, the fi sh's color
was evaluated with a colorimeter to measu re the chroma, lightness, redness and yellowness of different
color zones. The carotenoid and xanthophyll concentration in the skin and the scales of the fi sh's red,
black and white zones were tested. S. platensis signi fi cantly increased the growth and feeding ef fi ciency
of koi (P b 0.05). S. platensis and Carophyll® red signi fi cantly improved the chroma of the black zone,
the redness and the chroma of the red zone, and the lightness of the white zone (P b 0.05). S. platensi s
and Carophyll® red increased the caroten oid conte nt of the black and red scales and the xanthophyll con-tent of the black and red skin and scales (P b 0.05). The results indicate that Showa koi pigmentation can
be modi fi ed by supplementing the diet with 1.5 g kg − 1
Carophyll® red or 75.0 g kg − 1
S. platen sis. Dietary
R. palustris , at levels up to 1.0 g dry matter kg − 1
of diet, does not appear to affect the coloration of Showa
koi. Furthermore, body coloration was generally correlated with the dose of dietary caroten oids and xan-thophylls, and carotenoids had a deeper and greater in fluence than xanthophylls .