Fallow periods: Going Fishless

[1979fishgeek]

Day 19 of going fallow to treat white spot from my PBT. The pods in my DS think its awesome! Lol

 

[Congaken]

Going Fallow​

The reason to go fallow (fishless) is to eliminate a fish disease from your DT (display tank). Going fallow works because you are denying the disease a fish host to feed on, essentially starving it to death.

In order to go fallow you must remove ALL fish from your DT. If just one fish is left behind, even a “disease resistant” species, then going fallow is for naught because the disease will continue its life cycle. Corals/inverts can be left in the DT, as those are not capable of hosting - although some are capable of “housing” the encysted stage of certain parasites for a period of time (see “Fallow Periods” below). It is important to continue to feed your corals/inverts while going fallow, and also put a pinch of flake or pellet food into the DT every 2-3 days to feed nitrifying bacteria in the absence of fish poop. Continue to do everything normally with your tank while going fallow; although you may wish to go lights out if you are running a fish only system (just don’t forget to feed that bacteria!)

Fallow Periods - Below is the general consensus fallow periods for all diseases that require it. In most cases, it is the longest known time period that the encysted stage can survive on corals, inverts, rocks, substrate without a fish host to feed on. The fallow period starts when the last fish is removed from the tank.

• Black ich (turbellarian worms) - 4 weeks
• Brooklynella aka “Clownfish disease” or “Brook” - 6 weeks
• Gill Flukes (worms) - 4 weeks
• Ich (Cryptocaryon irritans) - 76 days
• Uronema marinum - No fallow period, as it does not require a fish host to survive. It is an opportunistic parasite that strikes when a fish’s immune system has been compromised. Uronema mainly affects damsels (especially chromis) and clownfish.
• Velvet (Amyloodinium) - 6 weeks

During the fallow period, the fish must be quarantined and treated for whatever disease(s) are afflicting them (see links below). Successful treatment is imperative to avoid disease(s) from being reintroduced into the DT:

https://www.reef2reef.com/forums/fish-disease-treatment-diagnosis/189284-fish-diseases-101-a.html

https://www.reef2reef.com/forums/fi...is/189658-treatment-options-my-two-cents.html

Quarantining all future livestock purchases is also very important to avoid having to go fallow again in the future: https://www.reef2reef.com/forums/fish-disease-treatment-diagnosis/189815-how-quarantine.html

After the fallow period has ended, you can return your fish to the DT. I recommend doing it one fish at a time, spread out over a couple of weeks. This will give your bacterial levels time to adjust to the added fish bio-load, and avoid a potential mini-cycle/ammonia spike. I also prefer to add back smaller fish first, so they are established ahead of the larger, more aggressive ones.

Do be sure to closely monitor your ammonia levels while adding fish back. I advocate using a Seachem Ammonia Alert badge for constant monitoring:

Edit: You can also use a FW black molly to test if your fallow period has been successful: https://www.reef2reef.com/threads/fallow-periods-going-fishless.190324/page-2#post-2855190

Humble...just want to tell you that my fallow period seemed to work well to eradicate the velvet on my Kole and potentially on the ff (who never showed it)...after the 6 week period, everyone went back to the 65 after a major wc...almost a week now...wish me more luck...Thanks...

 

[melypr1985]

Humble...just want to tell you that my fallow period seemed to work well to eradicate the velvet on my Kole and potentially on the ff (who never showed it)...after the 6 week period, everyone went back to the 65 after a major wc...almost a week now...wish me more luck...Thanks...

Hi! Im a little confused so I hope you can help me out here. A fallow period refers to leaving the display without fish to starve out a parasite such as velvet. So, I'm wondering how a fallow period eradicated velvet from a fish? Did you treat the fish in a QT then return said fish to the display after the fallow period? I'm sorry, I probably misunderstood your post and wanted to clarify in case I missed something.

 

[Humblefish]

Hi! Im a little confused so I hope you can help me out here. A fallow period refers to leaving the display without fish to starve out a parasite such as velvet. So, I'm wondering how a fallow period eradicated velvet from a fish? Did you treat the fish in a QT then return said fish to the display after the fallow period? I'm sorry, I probably misunderstood your post and wanted to clarify in case I missed something.

^^ This. I'm confused too.

 

[Congaken]

Hi! Im a little confused so I hope you can help me out here. A fallow period refers to leaving the display without fish to starve out a parasite such as velvet. So, I'm wondering how a fallow period eradicated velvet from a fish? Did you treat the fish in a QT then return said fish to the display after the fallow period? I'm sorry, I probably misunderstood your post and wanted to clarify in case I missed something.

Exactly what I did...copper for weeks...thanks to you as well and say "hi" to Lauren...

 

[melypr1985]

Exactly what I did...copper for weeks...thanks to you as well and say "hi" to Lauren...

Lol. That's what I thought. I knew I was misunderstanding the post. I'll tell her you said hi!

 

[Humblefish]

I reached out to Dr. Colorni, who co-authored the article which established the "72 day rule" for ich. Here is my email to him:

Dear Sir,

I am writing to you regarding this article you co-authored back in 1997: http://link.springer.com/article/10.1023/A:1018360323287

The part I have a question about is quoted below:

Even under identical incubation conditions tomonts vary considerably in the time required to form theronts (Nigrelli and Ruggieri, 1966; Colorni, 1992; Burgess and Matthews, 1994a; Diggles and Lester, 1996b). Thus, theront excystment is very asynchronous, occurring between 3 and 72 days and peaking at 6 ± 2 days (Colorni, 1992). This differs significantly from I. multifiliis, where the theront excystment takes only 18-24 h at 23C (Dickerson and Dawe, 1995).

The reason for asynchronous excystment is unclear. There is no relationship between the tomont size and excystment time (Nigrelli and Ruggieri, 1966; Colorni, 1992; Diggles and Lester, 1996a,b). In fact, a large and a small tomont may produce theronts at the same time, even though the smaller tomont undergoes fewer divisions. When tomites do not form until at least 2 weeks, a mass of endoplasm remains undifferentiated and fewer live theronts are produced (Colorni, 1992). Whatever the cause, asynchronous excystment prevents simultaneous exhaustion of all tomonts, facilitates theront dispersal in time and appears so advantageous to C. irritans that the phenomenon should be interpreted as a strategy for survival (Colorni, 1985).

And also this section:

The Australian trophonts stayed on the fish longer, tomonts took longer to excyst and the theronts were larger when fish were infected at 20C compared to 25C (Diggles and Lester, 1996a).

As I am sure you are aware, 72 days is an unusually long time to take for theronts to excyst from tomonts. In most other studies I've seen, 35 days was the longest time it took for theront release. Do you think the cooler 20C water temperature was directly responsible for the prolonged excystment period?

I am needing this information to help determine what might be the proper fallow period if a marine aquarium was infected with Cryptocaryon. I thought less than 72 days might be sufficient if the aquarium was being maintained at a more "reef-like temperature" of 25C, for example. Your expertise in this matter would be greatly appreciated.

Kind regards,
Bobby

Dr. Colorni graciously took the time to respond to me and his reply can be found below:

Dear Bobby,

Thank you for your (continuous) interest in my work.

Undoubtedly, low temperature slows down Cryptocaryon’s metabolism and thus lengthens its life cycle. Indeed 72 days were an exceptional period, but it occurred with the aid of antibiotics in a sterile flask. In nature (and in an aquarium), over more than two months, I would expect bacteria to “gnaw” on the tomont and eventually damage it.

In conclusion, a combination of “reef-like” temperature and non-aseptic conditions should make a quarantine period “less than 72 days”. How long such period should be presumed to be safe remains a difficult question. The bug has millions of years of evolution on its side...!

Sorry I can’t give you a more clear-cut answer.

Keep up the good work,

Angelo

**********************************************************************

Angelo Colorni, Ph.D., Senior Scientist
Retired ! Former Head, Dept. of Pathobiology

National Center for Mariculture
Israel Oceanographic and Limnological Research

- P.O.Box 1212, Eilat 88112, Israel

Research Website: www.ocean.org.il

**********************************************************************

Life is a whim of several billion cells to be you for a while.

 

[Humblefish]

Without a clear-cut answer, I feel it is advisable to continue to go fallow for 72 days (actually 76) for marine ich.

 

[jsiker]

I just had to go through a fallow period on my main tank as well. Lost a few fish before I got the QT up and everyone dosed in copper, but some did survive. All surviving fish have been put back in DT along with the new (and QT'd) additions.
One observation though, I did leave my corals in the DT as recommended but I noticed a total crash of nitrates in the tank by the end of the fallow period, which ended up costing me some of my Zoa's and a few others. I really hadn't put that into my routine to check (I'm still very much a noob) but I was wondering if maybe that is something worth mentioning/adding to the initial posting? I followed everything as best as I could (including going longer than even the 76 days) but didn't even THINK about the nitrates dropping to nothing affecting the corals.
Other than this, the fallow period and a solid QT now in place has my DT and "refugium" tank clean and disease free for the moment, so I appreciate all the guides to both going fallow and setting up a reliable QT system.

 

[edosan]

You are absolutly right! you must keep feeding your tank and monitoring No3 and Po4 levels drastic changes are not good.

 

[Humblefish]

Hadn't considered No3 and Po4 levels dropping drastically during a fallow period. Thanks @jsiker for the heads up!

 

[jeff williams]

Hadn't considered No3 and Po4 levels dropping drastically during a fallow period. Thanks @jsiker for the heads up!

What do you think about dosing ammonia during the fallow period every few days to feed the nitrifying bacteria

 

[ebushrow]

The ammonia alert is what you use? Never had luck with them.....maybe I'll need to try them again! Maybe I've been using them wrong or they were old.. Thanks for the post for them!

Fishless tanks are one of the hardest things to have and for 76+ days it seems impossible...but the benefits outweigh the lack of movement in the tank

Thanks as alway @Humblefish for the posting this!

 

[jeff williams]

The ammonia alert is what you use? Never had luck with them.....maybe I'll need to try them again! Maybe I've been using them wrong or they were old.. Thanks for the post for them!

Fishless tanks are one of the hardest things to have and for 76+ days it seems impossible...but the benefits outweigh the lack of movement in the tank

Thanks as alway @Humblefish for the posting this!

I think you may have misunderstood me , when the DT tank is fallow for 76 days there's nothing for the nitrifying bacteria to eat so when you add back the fish from qt you may have an ammonia spike. So during the fallow period dose ammonia to the DT so the nitrifying bacteria don't die off. Dose thank make sense?

 

[melypr1985]

So during the fallow period dose ammonia to the DT so the nitrifying bacteria don't die off. Dose thank make sense?

This can easily be accomplished by feeding the corals a couple times a week. That's all that's needed to keep the bio filter going.

 

[ebushrow]

I think you may have misunderstood me , when the DT tank is fallow for 76 days there's nothing for the nitrifying bacteria to eat so when you add back the fish from qt you may have an ammonia spike. So during the fallow period dose ammonia to the DT so the nitrifying bacteria don't die off. Dose thank make sense?

I think you quoted me by accident...

 

[jwshiver]

I am a week and a half into a fallow period. I apologize if this was covered and I missed it , but if the DT tank must sit fallow for 76 days then should the QT stay at therapeutic levels of copper for 76 days?

 

[melypr1985]

I am a week and a half into a fallow period. I apologize if this was covered and I missed it , but if the DT tank must sit fallow for 76 days then should the QT stay at therapeutic levels of copper for 76 days?

No. the copper levels stay there for 30 days. Observation and feeding happens for the rest of the time.

 

[jwshiver]

No. the copper levels stay there for 30 days. Observation and feeding happens for the rest of the time.

OK, Thanks

 

[Mark Gray]

Very good reading Thanks