Principle of Fish Nutrition

• Rotifers (Phylum Rotifera): Commonly referred to as wheel animalcules because the synchronous beating of cilia on their anterior crown (corona) resembles a rotating wheel under microscopic magnification.
• Significance as Live Feed:
• Species such as Brachionus plicatilis (L-type) and Brachionus rotundiformis (S-type) are indispensable starter live foods for early marine and freshwater fish and crustacean larvae due to their small size ($100-300\ \mu\text{m}$), slow swimming speed, and ease of nutrient enrichment (bioencapsulation with PUFA and vitamins).
• nalysis:
• (Rotifers): Correct.

Correct option: (2) Rotifers