Mineral requirements in fish. III. Calcium and phosphorus requirements in carp.

Carp were fed on diets containing different levels of calcium and phosphorus. The rearing water contained 20ppm calcium and 0.002ppm phosphorus. The growth rate correlated positively with dietary phosphorus levels but not with calcium levels. Feeding with a low-phosphorus diet resulted in reduced growth, low feed efficiency and deformity of the head. Dietary phosphorus levels affected greatly the ash, calcium and phosphorus contents of the vertebrae. Radiography of the fish receiving a low-phosphorus diet showed an insufficient development of the bones. The available phosphorus level in a diet producing the maximal growth was found to be 0.6 to 0.7%.