Nutrition, Supplementary Feeding and Pond Fertilization
This domain tests feed formulation, feeding rates, FCR and pond fertilization for natural food. Expect calculations and questions on when to feed versus when to fertilize.
Core rules
- Carp diets commonly use protein-rich ingredients such as groundnut oil cake, soybean meal, rice bran and fish meal; fry need more protein than grow-out fish.
- Feed daily at about 3–5% of fish body weight, adjusting for size, temperature and natural food. Overfeeding wastes feed and fouls water.
- FCR = feed given ÷ live weight gain. Lower FCR means better feed efficiency.
- Fertilization encourages plankton. Organic manures and inorganic fertilizers supply nitrogen and phosphorus; use after pond preparation and in split doses.
- Do not fertilize heavily when dissolved oxygen is low; plankton bloom can crash and cause oxygen depletion.
Worked example
A pond holds 100 kg fish. Feed at 3% body weight for 30 days. Daily feed = 100 × 0.03 = 3 kg; total feed = 3 × 30 = 90 kg. If FCR is 2.0, expected gain = 90 ÷ 2 = 45 kg. Reasoning: FCR is feed divided by gain, so gain is feed divided by FCR.
Traps
Do not invert FCR. Do not calculate feed from pond area alone without fish biomass. Do not assume fertilizer replaces feed in semi-intensive culture. Do not increase feed when fish are gasping at the surface; check oxygen first.