eChapter Name: Effect of Dietary Carotenoids on Body Pigmentation of Blue Gourami Trichogaster trichopterus
9789358872057
eBook Name: LIMNOLOGY AND MARINE BIOLOGY
by Anurag Protim Das, Shyama Prasad Biswas
INTRODUCTION
An expanding aquaculture industry that offers high incomes and job opportunities to people worldwide is ornamental fish farming. With over 2 billion live ornamental fish traded globally, the ornamental fish trade has become a very lucrative sector (Das & Biswas, 2016; Katia, 2001) with global net worth of more than 20 billion USD. According to Saxena (1994), the most significant factor influencing an ornamental fish's market value is its vibrant body colouration. Fish are incapable to synthesize carotenoids De novo (Goodwin 1951),and rely on dietary carotenoids for its body pigmentation (Hata and Hata, 1973). So, there is hence a direct correlation between pigmentation and dietary carotenoids(Halten et al., 1995). Aquatic animals' skin, meat, shell, and exoskeleton are coloured red, orange, and yellow due to a class of naturally occurring lipid-soluble organic pigments called carotenoids (Pailanet al., 2012). Fish skin and muscle colour regulation is significantly influenced by dietary carotenoids (Ahilan et al., 2008). The freshwater ornamental fish industry has encountered the issue of fadingfish body colouration, particularly in cases where the fish are reared in captivity for extended periods of time and subjected to rigorous cultivation conditions (Das and Biswas, 2016). According to Das and Biswas (2016), an ornamental fish's food should generally be nutritionally balanced, appetizing, resistant to crumbling, water stable, buoyant, and enhance or retain the fish coloration.
The phenomena of coloration in fish are quite significant and have a direct impact on its aesthetic value. If pigment-enriched feed can be prepared and used to increase coloration, the fish will undoubtedly have better quality and a cheaper price tag. Detailed research on colour enrichment in native ornamental fish using formulated feed is lacking (Das and Biswas, 2016). For the purpose of colour enrichment in fish, native plant sources have been used. Choubert (1979), Boonyaratpalin and Phromkunthong (1986), and Alagappan et al. (2004), utilized spirulina as a source of carotenoid colours for fancy carp and rainbow trout. Enhancement of pigmentation of Cyprinus carpio and Carassius auratus with microalgal biomass supplementation has demonstrated that Chlorella vulgaris is just as effective as synthetic colours (Gouveia et al., 2003). Alagappan et al. (2004) observed increased body pigmentation in Trichogaster trichopterus using Spirulina sp. algae as a source of carotenoid pigment. The body pigmentation of goldfish (Carassius auratus L.), red swordtail (Xiphophorus helleri), and tiger barb (Puntius tetrazona) was enhanced by feeding with marigold petal diet (Boonyarapatin and Lovell, 1977; Ezhil et al., 2008; Alma et al., 2013). Using natural sources of carotenoid pigments to improve the colour of ornamental fish is a cost-effective and ecofriendly solution. Due to the aforementioned information, the current study was carried out to assess how dietary natural carotenoids from source such broccoli (Brassica oleracea var. italica) effects the development and coloration of Blue Gourami, Trichogaster trichopterus, one of the important ornamental fishes with high market value.