Ontogenetic Sensitivity of Channel Catfish to Ascorbic Acid Deficiency

Abstract

Abstract Two distinct nutritional experiments were conducted sequentially with fry of channel catfish Ictalurus punctatus. Initial weight of fish was 0.030 ± 0.003 g in experiment 1 and 1.36 ± 0.03 g in experiment 2. In both experiments, fry were fed a semipurified, casein–gelatin-based diet containing no ascorbate supplement (AA-free) or a diet supplemented with 640 mg ascorbate/ kg as ascorbyl monophosphate (AP); fry used in experiment 2 had been given the AP-supplemented diet in experiment L Fish fed a diet devoid of vitamin C showed significantly reduced growth after 14 d in experiment 1 and 28 d in experiment 2. In experiment 1, fry fed starter feed lacking vitamin C showed significantly increased mortalities during the sixth through eighth weeks. At the same time, gross clinical signs of deficiency appeared, such as darker skin pigment, scoliosis, lordosis, and eroded fins. In experiment 2, larger fry did not show any mortality or external pathologies during the 54 d of the feeding study. The ascorb...