Which pigment is commonly included in ornamental fish feed to promote bright coloration?

• A. Protein
• B. Carotenoids
• C. Nitrates
• D. Zooplankton

Answer: (B)

Carotenoids are pigments added to ornamental fish feed to boost color. Many ornamental fish cannot synthesize carotenoids on their own, so their brightest reds, oranges, and yellows come from what they eat. When dietary carotenoids like astaxanthin, canthaxanthin, or beta-carotene are included in the feed, these compounds accumulate in the skin, fins, and eyes, giving vibrant coloration. Protein in the diet supports growth and overall health, but it doesn’t directly create vivid coloration. Nitrates relate to water quality and don’t contribute pigments, and high nitrate levels can even stress fish and dull colors. Zooplankton is a natural food source that can carry pigments, but the standardized way to enhance color in formulated feeds is through carotenoid additives.