I have recently returned my fish to my main tank, a 65 g, after treating two weeks for ichthyophthiriasis. Two days after treatment ended, I transferred my larger fish home to a fully planted tank and the flashing symptom was relieved. I left the 9 guppies to cycle the tank.

How do I handle the sky high counts (nitrites 0.5 ppm, nitrates 80 ppm, no ammonium, measured with heavy Prime), and how long before I know my fish are totally clean?

I also cooked my 65 at 80 for two weeks, the first 5 days at 89.


Disclaimer: I keep goldfish and the tank is not heated.

Ich, as far as I recall, has a lifecycle, and it’s called "white spot" in the UK. The copper-based medicine I used recommended treating over a 6 day period because Ich lives on the fish, then drops off and forms "pustules" which then burst and the new ich goes back on the fish. Wikipedia actually explains it but uses much more technical terms, and also with a temperature variation far outside the regions in my tank. The ich cannot be killed on the fish or in the "pustule", so the Ich treatment schedule was timed to maximise dosage at the best points when it was in the water.

All that is a pretty complicated way of saying you should know they’re clear in about 6 days. But you’ll be worrying about it for weeks.

That said, I always got the feeling the older goldfish developed a certain resistance to Ich because when it came again (after buying new fish, no matter how careful I thought I was), only the new fish got it.

Now, your chemistry. I don’t think your numbers are deadly but they’re not perfect. Water change to dilute them, 25% seems to be recommended. Add more filter bacteria. Keep cycling the tank. Check you haven’t lightly sautéed your plants (decaying plant matter can mess up the chemistry, too). Living, healthy plants will eat nitrates, decaying plants will produce ammonia (to nitrites, to nitrates if your filter is working). Watch the fish.

Hope that helps. There are some better fish experts on here than me, so hang tight and hopefully a tropical fish expert will give a more specific answer.

  • Thanx. The hospital tank has plastic plants, as real ones would melt with copper and salt, my recipe, along with lots of heat. The big tank had minimal plant loss, mainly Hornwort shedding, due to an earlier failed round with Ich X. My numbers are fine there. I kept it cycled with shrimp and a frog. It's just this darn hospital. But now that the waste load is greatly lightened, I expect better results in the near future
    – John Gern
    Oct 14 '19 at 22:19
  • Ok, did you treat the fish as well as the tank? I suspect the lack of outlet (I.e. plants) for the nitrates in the hospital tank means that water changes will have to be done.
    – Pam
    Oct 15 '19 at 7:15
  • I did not treat the main tank, just the fish. I removed all fish for 16 days. My plants, invertebrates and frog will not tolerate treatment
    – John Gern
    Oct 15 '19 at 8:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.