My parrot fish has thread-like growths after metronidazole. Treatment?

Metronidazole is used as an antibiotic against anaerobic bacteria in aquaria as well as an antiprotozoal medication. Dosing will depend on the concentration of the product as well as the size of the tank. Follow label directions carefully and remove the carbon filter insert during treatment.

Pimafix is an acceptable "natural" antifungal treatment. Melafix is for bacterial infections. Kanamycin, erythromycin or metronidazole are good broad spectrum antibiotics. Fungus Cure (by API) is an excellent antifungal. You can find these medications in the aquarium section of most pet stores or even online. Follow label directions carefully and remove the carbon filter insert during treatment if indicated. The cornerstone of any treatment is to first maintain pristine water quality and stable chemistry.

Thanks for reaching out about Thicket and including photos. Metronidazole is a fairly good broad spectrum antibiotic with some anti-parasitic (flagellates) activity. But no antibiotics treats everything and if the clinical signs are not improving, adding a second antibiotics might be helpful. Monitor environmental temperatures and humidity. Keeping nutritional intact high will also help. Good luck.

Thanks for reaching out about your parrot fish and including a picture. Unfortunately the picture does not help to identify the lesion. There are multiple parasites (and different treatments) that can infest the gills, but very few are visible to the naked eye. Anchorworms would be one such parasite. A short (5-15 minute) fresh water dip can help to decrease parasite loads. Fresh water should be well aerated with an airstone, and monitored the entire length of the treatment. A visit to the veterinarian would allow a gill and skin scrape to identify the parasite, and therefore prescribe a more precise treatment. Good luck.

Make sure the charcoal/carbon is removed from the filter/tank for the duration of treatment or it will remove/absorb the medication. Try using metronidazole and kanamycin. There is metronidazole in the Parasite Guard but it may not be an adequate dose. Monitor water quality and keep nitrates below 20ppm if possible. Use only aged/conditioned water that is temperature an pH matched to reduce or prevent stress. Raise the water temp to the upper limit for Oscars and add a multivitamin. You can soak pellets prior to feeding. If you can find it, use VitaChem (by Boyds). Make sure Tiger is eating a biologically appropriate diet.

It could be Columnaris, aka cottonmouth. It looks like a fungal infection but is actually an infection caused by a gram negative bacteria. You can treat with kanamycin and nitrofuran. Both are antibiotics effective against this bacteria. Brand names are Kanaplex (by SeaChem) and Furan 2 (by API). You can find them online or in the aquarium section of the local Petco. Follow label directions carefully and remove the carbon filter insert during treatment if necessary. You will likely need to treat the entire tank since more than one fish is symptomatic.

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.