Signs of illness

Most species of fish have a very fragile state of health and will rapidly deteriorate if they become ill or are in inadequate conditions. For this reason, any signs of illness or abnormal behaviour must be acted upon immediately. Due to fish being housed together in large numbers, the health of many animals can be at risk. Any ill animals must be removed from the other animals immediately and placed in a suitable quarantine tank. The other animals must be very closely monitored to ensure they are not displaying similar signs of illness.

Signs of illness include:

• Skin lesions
• Spots, fin erosion
• Gross colonies of bacteria
• Ulcers or growths
• Floating, listing
• Swelling of the body cavity
• Swimming upside down.

If any signs of illness or abnormal behaviour are displayed, quarantine sick animals, closely monitor all animals, take note of the other fish behaviour, test water quality, temperature and pH, oxygen level and contact an expert to identify the cause of illness. Regular monitoring of the water is essential to maintaining a healthy aquaculture enterprise. It is also important to closely monitor any filtration, aeration and cleaning mechanisms to ensure that they are working properly.