Optimum protein requirement of Cobia fish:

Correct option is C

Correct Answer: (c) 45%
Explanation:
→ Cobia (Rachycentron canadum) is a fast-growing marine fish; juveniles and grow-out diets commonly require ~40–50% protein, with ~45% often cited as optimum for rapid growth and feed efficiency.
→ Protein level should be balanced with energy (lipid/carbohydrate) to avoid protein wasting.
Information Booster:
→ Dietary needs vary by life stage: juveniles need higher protein than adults. Formulations and fishmeal replacement strategies are used to optimize cost.
Additional Information (Other Options):
(a)/(b): Likely suboptimal for juveniles; (d): may be excessive and uneconomical for routine feeds.