Gill Rot — caused by the fungal pathogen Branchiomyces sanguinis — is one of the most lethal diseases affecting Clarias gariepinus in Nigerian ponds. Mortality rates can reach 50–80% if not treated within 48–72 hours of first symptoms.
Gill Rot is a fungal infection of the gill tissue in freshwater fish, primarily caused by Branchiomyces sanguinis and Branchiomyces demigrans. The fungus invades the blood vessels inside the gill lamellae, blocking oxygen exchange. As the infection progresses, gill tissue dies and rots — giving the disease its common name.
In Nigerian catfish farming, Gill Rot is most commonly seen during the dry season (November to March) when water temperatures rise above 28°C and organic matter concentrations peak. Overstocked ponds with poor aeration are highest risk.
Gill Rot thrives in specific conditions that are common in Nigerian catfish ponds:
Gill Rot treatment must be aggressive and immediate. Nigerian farmers have access to the following effective treatments:
Increase aeration immediately. Run all available aerators at maximum. If you have a generator, use it. Oxygen depletion kills faster than the fungus in the acute phase. Do a 30–50% water change if dissolved oxygen is below 4mg/L.
Dissolve food-grade NaCl (iodine-free table salt or agricultural salt) at 2–3 grams per litre of pond water. For a 10,000-litre pond: 20–30kg of salt. Dissolve in a bucket of water first, then distribute evenly. Salt disrupts the osmotic environment of the fungus and reduces secondary bacterial infection. Repeat on Day 3 if mortality continues.
Potassium permanganate (available at most agricultural chemical shops in Nigeria) at 2–4mg/L as a pond treatment. It oxidises and kills the Branchiomyces spores in the water column. Do not exceed 4mg/L — it is toxic to fish at higher concentrations. Treat in the morning when oxygen levels are highest.
Malachite green at 0.1mg/L is highly effective against Branchiomyces. Available from aquaculture suppliers in Lagos, Ibadan, and Port Harcourt. Apply as a single treatment. Note: use is restricted in some export fish — if your fish are for domestic consumption this is not a concern.
Dead fish must be removed every morning and evening. Decomposing fish release massive quantities of Branchiomyces spores and ammonia, reinfecting healthy fish and crashing oxygen levels.
Yes. Branchiomyces spores are waterborne. Water transfer equipment, nets, and hands can carry spores from an infected pond. Always disinfect equipment between ponds using 10% bleach solution or potassium permanganate.
Brown gills with continued feeding is more likely early-stage Gill Rot or Aeromonas gill disease. Start salt treatment immediately and increase aeration. If feeding stops within 24 hours, escalate to full treatment protocol.
Gill Rot affects gill tissue primarily — fish gasp and show gill discoloration. Ich (white spot disease) shows as white pinhead spots on the body and fins. Both are treated with salt but Gill Rot requires higher doses and faster response.
Describe your fish's exact symptoms to MyFishDoc AI Doctor. It knows your pond's pH history, fish count, and FCR — and gives you a diagnosis in seconds.
Get Free AI Diagnosis