Table 12a. The presently known gross clinical signs of vitamin and amino acid deficiency in North African catfish Clarias gariepinus
Nutrient	Deficiency sign	Minimum�	Source
		requirement
Vitamins
Vitamin C	Erratic swimming, flashing, skin darkening and reduced growth	50 mg/kg diet	Adham et al., 2000; Adewolu and Aro, 2009
Niacin	Feed refusal, listlessness, weight loss, poor feed utilization, high mortality, haemorrhagic skin and severe anaemia	33.1 mg/kg diet	Morris, Baker and Davies, 1998
Amino acids
Tryptophan	Reduced growth, deformed vertebral column and anorexia	1.1 % of dietary protein	Fagbenro and Nwanna, 1999