Devastating effects can occur once pathogens have been introduced into a recirculating system. Pathogens are almost impossible to eradicate. Eradication of the system consists of depopulating the system; sterilizing it; and then repopulating it. At the conclusion of this process, some pathogens may have survived. Even with 100% success the outcome can be fatal to farmers who are depending on their tilapia farm for revenue.
Streptococcus: Streptococcus causes one of the most significant bacterial diseases, particularly in indoor systems, some of the resulting symptoms are; sluggishness, weakness, no appetite, red discoloration at the anus, red discoloration at the base of fins, hemorrhagic eyes, gills, internal organs and muscle, blood tinged abdominal fluid, swollen kidney, spleen and liver, erratic spiral spinning, curved body, opaque cornea in one or both eyes, protruding eyes and abdominal distention.
The administration of antibiotics does not really control streptococcal infections because the withdrawal period for the antibiotics is longer than it takes for the infection to return. Streptococcal strains are constantly becoming resistant to newly developed antibiotics.
Vaccines can be injected into the infected fish but this can be time consuming and costly since each fish must be injected individually. The cost of vaccination is higher than the cost of the fish.
Loss of appetite caused by the disease reduces the growth rate significantly. If they make it to market the fish have a markedly reduced shelf life.
Aeromonas: Inadequate water quality in a system or overcrowding can cause affection by aeromonas which is another bacterial disease and significantly alter a farms yield. This disease will momentarily respond to antibiotic therapy, the source of fingerlings really needs to be changed. Symptoms of Aeromonas are; lethargy, weakness, loss of appetite, red discoloration at the anus, red discoloration at the base of fins, hemorrhagic eyes, gills, internal organs and muscle, blood tinged abdominal fluid and swollen kidney, spleen and liver.
Trichodina: Young fish are more susceptible to trichodina then mature fish. Trichodina is a protozoan parasite that can result in very high rates of fatality. This parasite attacks the gills. Infected fish will display; flashing (trying to scrape off parasites by scraping against the floor of the tank), pant-like breathing, weakness and haphazard swimming. With the gills operating less efficiently, affected fish have trouble; absorbing oxygen, giving off carbon dioxide and excreting ammonia.
Copper Sulfite and salt, or formalin can temporarily control populations infected with Trichodina. It is nearly impossible to rid a system of trichodina. Any fish coming to you from outdoor ponds should be examined carefully.
Columnaris: Columnaris is a disease that is caused by myxobacteria, which is a group of bacteria that live in the soil and typically travel in swarms. An outbreak of this disease is usually caused by temperature fluctuations, trauma and poor water quality. The use of outdoor surface water is very risky for fish. Poor nutrition and overcrowded conditions can also increase the intensity of the disease. Fish infected with columnaris will usually display the following signs; lethargy, anorexia, weak swimming, morality and raised white patches on the skin or fins. Copper sulfate and potassium permanganate may be effective temporarily.
Streptococcus: Streptococcus causes one of the most significant bacterial diseases, particularly in indoor systems, some of the resulting symptoms are; sluggishness, weakness, no appetite, red discoloration at the anus, red discoloration at the base of fins, hemorrhagic eyes, gills, internal organs and muscle, blood tinged abdominal fluid, swollen kidney, spleen and liver, erratic spiral spinning, curved body, opaque cornea in one or both eyes, protruding eyes and abdominal distention.
The administration of antibiotics does not really control streptococcal infections because the withdrawal period for the antibiotics is longer than it takes for the infection to return. Streptococcal strains are constantly becoming resistant to newly developed antibiotics.
Vaccines can be injected into the infected fish but this can be time consuming and costly since each fish must be injected individually. The cost of vaccination is higher than the cost of the fish.
Loss of appetite caused by the disease reduces the growth rate significantly. If they make it to market the fish have a markedly reduced shelf life.
Aeromonas: Inadequate water quality in a system or overcrowding can cause affection by aeromonas which is another bacterial disease and significantly alter a farms yield. This disease will momentarily respond to antibiotic therapy, the source of fingerlings really needs to be changed. Symptoms of Aeromonas are; lethargy, weakness, loss of appetite, red discoloration at the anus, red discoloration at the base of fins, hemorrhagic eyes, gills, internal organs and muscle, blood tinged abdominal fluid and swollen kidney, spleen and liver.
Trichodina: Young fish are more susceptible to trichodina then mature fish. Trichodina is a protozoan parasite that can result in very high rates of fatality. This parasite attacks the gills. Infected fish will display; flashing (trying to scrape off parasites by scraping against the floor of the tank), pant-like breathing, weakness and haphazard swimming. With the gills operating less efficiently, affected fish have trouble; absorbing oxygen, giving off carbon dioxide and excreting ammonia.
Copper Sulfite and salt, or formalin can temporarily control populations infected with Trichodina. It is nearly impossible to rid a system of trichodina. Any fish coming to you from outdoor ponds should be examined carefully.
Columnaris: Columnaris is a disease that is caused by myxobacteria, which is a group of bacteria that live in the soil and typically travel in swarms. An outbreak of this disease is usually caused by temperature fluctuations, trauma and poor water quality. The use of outdoor surface water is very risky for fish. Poor nutrition and overcrowded conditions can also increase the intensity of the disease. Fish infected with columnaris will usually display the following signs; lethargy, anorexia, weak swimming, morality and raised white patches on the skin or fins. Copper sulfate and potassium permanganate may be effective temporarily.
About the Author:
One fish that has always been popular for use in aquaponics is tilapia. It has always performed well in recirculating systems. Unfortunately so have disease-producing microorganisms called pathogens.. Check here for free reprint license: Diseases of Tilapia.