Climate change, temperature change, water pollution/contamination, influx of sewage water, metal content,contamination with CO2, NH3 etc.
High stocking density, disease,
infections (bacteria, viruses, parasites), chemical medication etc.
Irregular feeding or nutritional
deficiency
Impaired collagen synthesis &
shell formation (Vit. C deficiency leads to distortion of cartilage, hyperplasia of gill tissue, scoliosis, lordiosis etc.)
Poor spawning success, fertility
and hatchability
Post-hatch mortality of
fingerlings (incorporation of ascorbic acid in the egg during ovarian growth is
important for successful larval development after hatching)