Abstract:
Koi is an economically important fish variety because of the wide diversity of skin color
patterns. Fishes are unable to synthesis carotenoids in their body. The culture of
ornamental fish without supplementation of dietary carotenoids leads to fade coloration.
But synthetic carotenoids are expensive. Marigold petals (Tagetes erecta) and banana
peels (Musa acuminata) are inexpensive, abundant, rich in carotenoids, and discarded as
wastes. The objective of this study was to develop a suitable color enhancing fish feed
and enhance the skin color of Koi carp by using natural color pigments. An experiment
was carried out for nine weeks to enhance the body coloration of Koi carp under
laboratory conditions. Four weeks old, 252 Kohaku fish were randomly introduced into
seven treatments with triplicates. Marigold petals and banana peels were sundried, ground into fine particles, and sieved. Color enhancing diets were prepared with
different concentrations (5, 10, 15%) of sun-dried marigold petal powder and banana peel
powder; with the control treatment; commercial fish feed. All seven feed types were
analysed for crude protein, crude lipid, ash, and moisture. Feed samples were checked for
changes in physical properties at room temperature and refrigerated conditions (4 ºC) for
one month. The total carotenoid concentration of all diets was measured using a UV
spectrophotometer. The color analysis of the fish skin was done by a photographic
method using Image J software. After 9 weeks from feeding, maximum skin coloration of
Kohaku fish was achieved by the feed incorporated with 15% Marigold petal powder and
15% banana peel powder with significantly different. (p<0.005). Marigold petal
incorporated feed obtained high skin coloration than banana peels. The lowest skin
coloration was achieved in commercial fish feed. The growth rate of fish did not show
any significant difference among prepared feeds during the trial. This study showed that
prepared diets using Marigold petals and banana peel with different concentrations
provide adequate enhancement of coloration for Kohaku fish with a short time.
Keywords: Kohaku Carp, Fish feed, Skin coloration, Marigold petals, Banana peels
