Vol. 10, Issue 1, Part B (2026)

Keeping ornamental fish is the second hobby globally. The vibrant and lucrative colour variation of any ornamental fish fetch more money or profit to the breeders and culturists. The prominent and long-lasting colour depends on the feeding to fish with natural carotenoids rich feed ingredients. The deposition or accumulation of colour pigment on skin, fin and flesh of ornamental fish is species specific. But the colour development is influenced by water quality parameters, temperature, photoperiod, and light intensity/quality, balanced feed and carotenoids sources. The majority of carotenoids are mainly C40 tetraterpenoid pigments and derived from two C20 geranylgeranyl pyrophosphate (GGPP) molecules. There are more than 600 known carotenoids that fall into two categories: i) Xanthophylls which include astaxanthin, lutein, and zeaxanthin and contain oxygen as a functional group, and ii) Carotenes which include lycopene and β-carotene and contain a hydrocarbon chain and no functional group. The carotenoids are also important for growth, reproduction, and disease resistance in fish. Different natural ingredients like marigold, papaya, rose petal, carrots etc. are used for colour enhancement of different fishes.