The most important cause of mortalities of eggs and larvae are fungal, parasitic and bacterial infections;
Fungal diseases
The most common fungal infection is caused by saprolegnia. the infected eggs/larvae are covered with a cotton-like growth. During the incubation of the eggs and larvae it is recommended to threat them with Malachite green 0.1–0.2 ppm once a day
Note: Make a stock solution of 10 gram of malachite green in 1 litre of water. A treatment of 0.1 ppm means that 1 ml of stock solution must be dissolved in 100 litres of water. Example: your basin contains 600 litres of water then you put 6.0 ml of stock solution in the basin and keep the water running.
Parasitic diseases
The most commonly found ecto-parasites are: Dactylogyrus, Trichodinia, Costia, Chilodonella and Gyrodactylus. fry and fingerlings can be treated with 20–25 ppm formalin.
Bacterial diseases
Two most common bacterial infection are caused by a myxo-bacteri (Flexibacter) and by an Aeromonas (oedemic disease). Both infections can be treated with antibiotics as; oxytetracycline (bath, 50 ppm for 5 days), Furataldone 10 ppm in combination with penicillin 10 ppm (bath, 4–5 days).
“crack head” disease is the only obvious catfish disease reported from pond culture upto present. The cause of this disease is not fully understood. Adverse water quality due to over feeding is believed to be the main factor causing “crack head” disease. The clinical symptoms are: slightly distended abdomen due to septicemia and haemorrhage and occasionally exophthalmus (pop-eyes). This disease can be detected in an early stage, affected fish show a reddish lateral line on the skull, between the two air chambers, parallel to the skull plate joints. In the final stage the skull will break laterally followed by death.
As soon as the external symptoms of the disease (reddish lateral line) is observed in some fish during sampling, feeding should be substantially reduced and pond water should be replaced. Generally, the fish recovers after a few weeks, after which feeding can be increased little by little.
