One of the reported roles of carotenoids is their antioxidant
role in animals. Trace amounts of reactive oxygen
species can decrease fertility in organisms [14,16]. Fish
sperm is sensitive to oxidant agents that destroy the fat
layer of sperm [17]. In many aquaculture farms, there has
been an attempt to improve egg and larvae quality, but
sperm quality has been ignored. Blount et al. [18] found
that male fishes transport carotenoids linked to lipoproteins
into testes to inhibit damage due to reactive oxygen
species. Other studies have shown that there are significant
positive correlations between carotenoid levels in the
bodies of male fish regarding sperm concentration and
motility [19]. These sperm enter into the ovule more
rapidly than other sperm during mating [20], resulting in
increased fertilization efficiency [21]. The efficiency of dietary
carotenoid supplementation on the growth, skin
coloration, and immune response of fancy carp was
investigated using locally common agricultural plant materials
as natural carotenoid sources [22].