Table 12b. Gross clinical sings of vitamin deficiency in Clarias batrachus
Vitamin	Deficiency sign
Thiamine	Dark skin colour
Riboflavin	Fragile fins; haemorrhaging under skin, fins and around eyes; eroded barbels; oedema; poor appetite; lethargy; pale gills and liver
Pyridoxine	Eroded barbels and fins, tetany, nervous disorders, loss of equilibrium, erratic swimming (whirling, twisting and swimming in circles) prior to dying fish surfacing and floating with rapid breathing. Internal organs appear normal.
Pantothenic acid	Reduced food intake, decreased activity, rubbing against bottom.
	Lesions and necrosis; clubbed gills, haemorrhaging under skin, fragile fins, oedema, eroded barbels, rapid breathing, swelling at base of pectoral fin, pale gills and liver, gills covered with excessive mucous.
Folic acid	Fish appear normal, but food intake is decreased; fading body colour, pale gills and liver.
Niacin	First sign is loss of appetite. Muscle spasms, loss of equilibrium, whirling, lethargy, haemorrhaging under skin and fins and slightly protruding eyes; prior to death fish dart to surface and immediately sink to bottom  with convulsions.
Ascorbic acid	Scoliosis, external haemorrhaging, fin erosion, dark skin colour. No abnormal postmortem features.
Note: Significantly lower growth rates and higher mortalities recorded in all vitamin-deficient groups except for vitamin C.
Source: Butthep, Sitasit and Boonyaratpalin (1985)