The nematodes deprive their host of food and can feed on host tissues, sera and blood causing emaciation and anaemia. Clinical signs of nematode infestation vary and can range from deformed body shape, haemorrhage, mortality, traumatic enteritis, loss of balance through damage to their swim bladder, reduced swimming performance, lethargy, reduced sexual display rate, ulceration of gill cover, fraying of fins, large nodules on the ventral surface of the skin and fish can be seen swimming or floating on their sides. Infected fish can be more susceptible to decreased oxygen content in the water. Pathogen such as Philonema and Philometra can cause atrophy or destruction of gonads, ascites and distension of the abdomen.