My fish are dying with white fluffy stuff. Melafix isn't working. Why?

Thanks for reaching out about Fish. Test and correct water quality for pH, ammonia, nitrites and nitrates. If all fish are affected, water quality problems the most likely. Alteration can lead to increased mucous production from the skin (white stuff), but fungal dermatitis or parasites are also possible. A veterinary visit is recommended if the water quality if appropriate, to assess and provide a diagnostic/treatment plan. Good luck.

Check the water chemistry. The discoloration could be due to elevated ammonia levels which can cause "burns". Use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Perform partial water changes to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. The Neons (blue fish) appear to be infected with Ich, a parasite. Treatment is possible with commercial products found in the local Petco. Follow label directions carefully. You will need to treat the entire tank until all traces are gone. Removing a lump from your fish on your own is never recommended. You can cause severe injury. Most broad spectrum antibiotics (Kanaplex, Maracyn, Maracyn 2, etc.) found in the aquarium section of the local Petco should help treat or prevent infection. Choose one and follow label directions. Remove the carbon filter insert during treatment if indicated. Maintain pristine water quality via filtration and regular partial water changes to aid in recovery. You can feed frozen worms, just thaw then first in a small cup then place them in the tank.

It is hard to tell from the picture if your fish has fungal plaques on the scales or if this is normal pigment. I would recommend taking your fish to a vet for a necropsy. That will allow for biopsies and cultures to be sent to the lab to determine the cause of death. IF it is fungal disease I would recommend treating the tank and cleaning the environment well.

Thanks for reaching out about your aquarium and including photos. Did you test your water quality prior to the water change? Continue to test for pH, ammonia, nitrites and nitrates. Pristine water quality is needed for health. Are any of the fish new, that could have introduced parasites? Itching/flashing can be due to water quality, external parasites, bacterial or viral infections and other causes. The white lesions on the photo could be fungal infections. A skin scrape and examination under the microscope (at a veterinarian's office) is needed for an attempt to determine a cause. Fungal infections are often secondary problems, so check water quality first. Good luck.

The white fuzz may be Columnaris, an infection causing bacteria, or a fungal infection. It can be difficult to differentiate without microscopic examination. Either can be managed/treated via partial water changes, plain aquarium salt (NOT table salt) and medications. Partial water changes, no more than 20-30% daily, will stabilize chemistry and maintain or improve water quality. Use only aged or conditioned water that is temperature matched to prevent additional stress or shock. Aquarium salt can be used at 1 tablespoon per 5 gallons of water. Dissolve in a few cups of tank water and gradually pouyr it into the tank. Treat for 10-14 days then reasses the condition. When performing water changes, treat only the volume of water being replaced, not the entire tank volume. A methylene blue dip can be done daily. You can find it in the aquarium section of the local pet or fish store. A concentration of 50ppm is recommended. Do not add it to the main tank as it will turn everything blue and kill beneficial bacteria in the filter and substrate. Use a separate container and dip the fish for a few seconds, rinse and return it to the main tank. In the future, quarantine any new fish for several days to prevent introduction of disease to existing populations.

It could be early ich (white spot) infection or another infection (bacterial or fungal). To be safe, separate him into a quarantine tank and monitor for any change. You can treat for ich as you did it in the past if indicated. Bacterial and fungal infections have different treatments, so I would be hesitant to recommend a specific medication without more information or a definitive diagnosis. You can use plain aquarium salt (NOT table salt or Epsom salt). As a general tonic to reduce stress, increase gill function, treat minor infection of many types and to aid in recovery. This can be added to the quarantine tank at 1 teaspoon per gallon of water. Treat for 10-14 days then reassess the condition.

If it is fuzzy, it is likely fungal. You can try with a commercial antifungal medication such as API Fungal Cure, methylene blue or Pimafix/Melafix. These can be purchased online or in the aquarium section of most pet stores. Read package directions carefully and remove the carbon insert from the filter before treatment if indicated. Plain aquarium salt (NOT table salt) can be used in conjunction with one of the above treatments to aid healing. Dissolve up to one tablespoon per gallon of water into the tank. Fungal infections can take up to two weeks to resolve with treatment. Maintain proper water parameters (0 ppm ammonia/nitrites, 40ppm or less nitrates and temp of 65 F to 72 F). If possible, remove the affected fish yo a hospital tank during treatment.