My goldfish's fins are turning black. I changed the whole water 2 days back. I put medicine after every water change. Still it's increasing. What should I do? And how often should I change the water and amount of water I should change? Can we substitute aquarium salt with any other things. Pet's info: Fish | Unknown - Fish

Elevated ammonia levels can result in "burns" which may turn fins and scales black. Use a home test kit or submit a water sample for testing. Most pet or fish stores will do this for free or for a nominal fee. If ammonia levels are elevated, daily partial water changes, using aged or conditioned water, can decrease ammonia to safe levels (0.25 ppm or less). StressCoat or plain aquarium salt (NOT table salt) can aid in healing. Dissolve 1 teaspoon of salt per gallon of water into a cup of tank water and gently pour it into the tank. Confirm adequate filtration. The filter should be rated for at least twice the volume of the tank. You can change 20-30% of the tank water every couple of weeks. Use only aged or conditioned water that is temperature matched to prevent stress or shock.

Check the water chemistry first. Elevated ammonia levels may result in a cloudiness to the eye(s). Use a master test kit (liquid, not strips) at home or submit a water sample for testing. Most pet stores will do this for free or for a small fee. Perform partial water changes daily, in indicated, to stabilize chemistry and maintain water quality. Use only aged/conditioned water that is temperature matched to prevent stress or shock. If chemistry is fine, it could be bacterial infection. A broad spectrum antibiotic, such as kanamycin, can be used for treatment. Look in the local pet store or Petco for "KanaPlex". It should be in the aquarium section. Follow label directions carefully and remove the carbon filter insert during treatment. Plain aquarium salt (NOT table or Epsom salt) can be used as a general tonic to reduce stress, improve gill function, treat minor infection and aid in recovery. Dissolve 1 teaspoon of salt per gallon of water in a cup of tank water and gently pour it into the tank. Treat for 10-14 days then reassess the condition. When performing partial water changes, treat only the amount of water being replaced, not the entire tank volume. Confirm the tank is large enough to support two goldfish. Ideally, you need about 20-30 gallons for the first fish and 10 additional gallons for each extra fish. Goldfish produce a larger than normal bio-load (wastes) that can quickly overwhelm a tank/filter. The filter should be rated for at least twice the volume of the tank.

That could be due to an old injury which is now resolving or possibly an initial fin rot disease. It is very important to monitor the development of this black spot and if getting bigger I would recommend a quite radical but logic approach. Begin by submitting a water sample for quality testing. Most pet stores will do this for free or a nominal fee. Clinical examination should always include a water quality check, even if you have done so already. Water testing should be performed with a quality test kit, measuring NH4, NO2 and NO3. High ammonia levels, PH imbalances may be responsible for these signs. Oxygen concentration and quality of the filters should be determined as well. If water quality is good and there are no major imbalances, your fish should get examined to look for any sign of bacterial/fungal infection and eventually water should be treated. Regarding the food, the requirements are very different as bettas are insectivores and goldfishes are mainly herbivores. Food for bettas are richer in proteins and should ideally not be used for goldfish but the other way round would be even worse, so between the two I would recommend betta's food. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.