Freshwater fish tuberculosis (wasting disease) is a contagious disease caused by the bacteria Mycobacterium marinum. This disease affects a wide variety of freshwater fish species, including common carp, goldfish, catfish, perch, and trout. The bacteria is spread through direct contact between infected and healthy fish or via contaminated water sources. Infected fish have signs of the disease such as appetite loss, weight loss, lethargy, skin lesions, fin and tail rot, and abdominal swelling.
The disease can be difficult to diagnose in its early stages because the signs are often similar to other illnesses. To diagnose freshwater fish tuberculosis, a veterinarian should take samples from the affected fish for laboratory testing. Treatment with antibiotics is possible but not guaranteed to be successful. Unfortunately, the disease is often fatal and can quickly spread throughout an entire tank or pond if left untreated.
Symptoms of Freshwater Fish Tuberculosis
- Appetite loss
- Weight loss
- Lethargy
- Skin lesions
- Fin and tail rot
- Abdominal swelling
- Trouble breathing
- Visible blood vessels on their fins and tail
- Cloudy eyes
Diagnosing Freshwater Fish Tuberculosis
A veterinarian should take samples from the affected fish for laboratory testing. This includes blood tests, tissue samples, and a bacterial culture. The results of these tests can help to confirm or rule out a diagnosis of freshwater fish tuberculosis.
Stages of Freshwater Fish Tuberculosis
Acute stage:
This is the initial infection period where clinical signs can include loss of appetite, weight loss, lethargy, skin lesions, fin and tail rot, and abdominal swelling.
Subclinical stage:
During this stage, the fish might not have any signs of the disease but can still be a carrier and spread it to other fish. It’s important to take precautionary measures, such as quarantining new fish and regularly testing existing fish.
Chronic stage:
This is the advanced stage of the disease where the affected fish can have open sores, visible blood vessels on the fins and tail, cloudy eyes, trouble breathing, and other signs of severe illness.
Treating Freshwater Fish Tuberculosis
The best way to treat freshwater fish tuberculosis is to use antibiotics. The antibiotic of choice is typically tetracycline or doxycycline, although other antibiotics can be used as well. It’s important to ask a veterinarian for advice before administering any medications.
Preventing Freshwater Fish Tuberculosis
To prevent the spread of freshwater fish tuberculosis, it’s important to quarantine new fish and regularly test existing fish. It’s also wise to practice good hygiene, such as wearing gloves when handling or cleaning tanks, and avoiding contact between infected and healthy fish. Make sure to change the water in the tank or pond on a regular basis to reduce the risk of infection.