How long to wait before adding new fish after ich treatment?

Ideally, the tank should be kept at about 86 F for two weeks to resolve Ich infection. The gravel or substrate should be vacuumed and tank furniture sanitized. If you are setting up the tank anew, you will have to allow time for it to properly cycle prior to adding fish.

Ich (Cryptocaryon) is an obligate parasite. This means it needs fish to survive. If your tank has no fish, continue to run the filter and tank empty for at least 6 weeks. You can increase temp to about 86 F to speed up the life cycle of the parasite. If your tank is not a reef tank and has no inverts, you can treat the tank with copper. Once treatment is complete, decrease temps to normal ranges. Continue to monitor salinity/chemistry. Quarantine any new fish for at least 10 days in a bare bottomed, established tank to prevent re-introduction of parasites into the main tank.

When there is an ich infection, it is necessary to treat the entire tank, even the fish that are not symptomatic. Ich has 3 distinct stages in the life cycle. Tomites, the free swimming stage, are most vulnerable to treatment. Once on the fish or encapsulated in the substrate, ich is very difficult to treat. A combination of increased water temp, aquarium salt and commercial medication can be used to treat ich. The increased water temp, 86F, will significantly speed up the lifecycle. It can take 1-2 weeks to treat minor infections and longer for more severe infections.

If a QT tank is not available, then prophylactic treatment can be done on new fish. Methylene blue or malachite green, providing your chosen fish are not sensitive to either, can be used on Day 1 and then again on Day 4. A commercial ich treatment can be used instead as well. Be sure to treat any plants as well.

Ideally you would quarantine any new Fish in a separate aquarium for a few weeks to make sure they do not show any signs of diseases or infection. Once 2-3 weeks have passed without any signs of a problem then it is usually pretty safe to introduce to the common aquarium. Good luck and I hope they do well!

Increase the temp, gradually, to 86 F and hold it there for at least two weeks. This will speed up the ich lifecycle. When the parasite is free swimming is when it is most susceptible to treatment. Once the spots drop off your fish, perform a major water change and vacuum the substrate thoroughly. If you have live plants, remove them and gently wipe them down, if you have artificial plants, remove them and sanitize them. The same goes for any tank furniture. Use the ich medication according to label directions. Keep the water temp elevated for 3-5 days after treatment and after all symptoms have resolved. Gradually reduce water temp back to normal afterwards. There is no definitive way to determine if the infection is resolved. You will to monitor the fish closely and repeat the process if necessary.

It is difficult to determine since the image is not clear. Fish are very hard to photograph! If it does, then it is very early infection. Ideally, new fish should be quarantined for at least 2 week sin a separate tank to confirm good health prior to introducing them into the main tank. Monitor for worsening symptoms. If necessary, you can purchase an ich treatment and treat the tank. Look in the Aquarium section of the local Petco. Follow label directions and remove the carbon filter insert during treatment if indicated.