Fallow Period with PCR Test Results

spartanman22 · Jul 9, 2026

I had an Ich outbreak in my DT last month. Something must have slipped through QT. So I pulled all the fish and am running through my fallow period. I’m currently on day 34. Fish finished copper today and are about to start Prazi.

I had a handful of DxAquaria PCR test kits and thought it’d be interesting to see how the results measure out at different stages of the fallow period. I took a sample on June 26th which was 22 days into fallow and had a cryptocarian count of 3 DNA/mL.

I also picked up a handful of black velvet mollies, pulled 3 gallons from the fallow DT and acclimated them to saltwater in a separate tank. It’s been 3 days and no signs of ich on them yet. I plan to take another PCR test end of next week. My 45 day fallow date is on July 22nd so it’ll be interesting to see what the second test comes back at. By the time I get the results back I should be right around that 45 day mark.

I’m just sharing this as I think it’s an intriguing new way to track fallow periods. These test kits aren’t quite cheap enough to be doing regularly (imo) at $50 a pop, but they’re reasonable enough to play around with a handful of times.

Jay Hemdal · Jul 9, 2026

spartanman22 said:
I had an Ich outbreak in my DT last month. Something must have slipped through QT. So I pulled all the fish and am running through my fallow period. I’m currently on day 34. Fish finished copper today and are about to start Prazi.

I had a handful of DxAquaria PCR test kits and thought it’d be interesting to see how the results measure out at different stages of the fallow period. I took a sample on June 26th which was 22 days into fallow and had a cryptocarian count of 3 DNA/mL.

I also picked up a handful of black velvet mollies, pulled 3 gallons from the fallow DT and acclimated them to saltwater in a separate tank. It’s been 3 days and no signs of ich on them yet. I plan to take another PCR test end of next week. My 45 day fallow date is on July 22nd so it’ll be interesting to see what the second test comes back at. By the time I get the results back I should be right around that 45 day mark.

I’m just sharing this as I think it’s an intriguing new way to track fallow periods. These test kits aren’t quite cheap enough to be doing regularly (imo) at $50 a pop, but they’re reasonable enough to play around with a handful of times.

What’s the water temperature?

Below 81f, I suggest people go with a 70 day fallow period just to be safe.

Now that Aquabiomics is closing, DxAquaria is the only game in town.