Why a fallow period will sometimes fail

[MamaP]

We've all seen claims of ich, velvet, etc. returning after a 76 day fallow period. (For anyone wondering what a fallow period means click here: https://www.reef2reef.com/threads/fallow-periods-going-fishless.190324/)

Oftentimes, a fallow period failure is due to human error: The sick fish weren't treated long enough or the treatment itself wasn't done properly, cross contamination via wet hands or equipment, aerosol transmission (more info). It is also possible that undiscovered strains of ich (and other diseases) exist; ones with a prolonged life cycle that exceeds what we know to be true from scientific research. However, there is also this possibility to consider:

Dormancy induced by a hypoxic environment in tomonts of Cryptocaryon irritans, a parasitic ciliate of marine teleosts


Highlights from the study:

• This study demonstrates that tomonts of Cryptocaryon irritans become dormant in hypoxic environments.
• Dormant tomonts resume development in oxic environments at any developmental stages.
• We examined tomont viability following variable sequences of oxic and hypoxic conditions.
• Dormancy in hypoxic environments may be key to the autumn outbreaks of cryptocaryoniasis in floating net cages in temperate waters.

So what does this mean for us and our fallow aquariums? Primarily, the study showed that an ich tomont (the "egg stage" which encysts to corals, inverts, rocks, etc.) can go dormant if the protomont crawls into a hypoxic (low oxygen) environment or anaerobic (no oxygen) region of your DT just before encysting. Examples of this include under your sand bed (especially a DSB), inside a non-porous rock, any "no flow" region of a canister or other aquarium filter. The study also demonstrated that once returned to an oxygen rich environment, these once dormant tomonts resumed their development and released theronts (free swimmers which seek out fish to infect.) How long can it take for a dormant tomont in a hypoxic environment to suddenly be exposed to an oxic (oxygen rich) environment? The world may never know?!

So what can you do to eliminate low oxygen areas of your DT during a fallow period?

1. Take any canister or enclosed filters offline, and sterilize them with bleach. Without fish to foul the water, your DT will be fine with just rock/sand for filtration and good water circulation.
2. Speaking of circulation, crank up those pumps for maximum flow & gas exchange throughout the aquarium. (Don't forget to add a pump down in the sump.)
3. Blow out your rocks (using a powerhead) and vacuum the sand during water changes whilst going fallow. This will "stir things up" and provide free oxygen to those areas.

How can I setup my Display Tank to be "hypoxic proof" just in case I ever have to go fallow?

1. Only use filtration with an open top (like a sump), and avoid canister filters and other filters which may contain anaerobic regions. If needed, take these offline if ever having to go fallow.
2. Use just a light layer of sand; the deeper it is the more likely tomonts can get "trapped" down under there.
3. Never have sand out of reach (i.e. under a rock) in case you need to vacuum it during a fallow period.
4. Only use very porous rock which will allow plenty of flow (and oxygen) to pass through.

More information on Marine Ich (Cryptocaryon irritans) can be found here: https://www.reef2reef.com/threads/ich-cryptocaryon-irritans.191226/

Hi, @Humblefish . I love reading your very informative posts. I have a question about this subject. I'm currently fallow in my DT. I have snails, hermits, and a shrimp in there, tho. I do have a canister filter (Fluval X4), live rock, and 1-2" live sand. I also have a few non-porous decorations in there. I had to take everything out of the tank to catch the fish for QT, which definitely stirred up the sand. Should I take apart and sterilize the canister and all media in it and wipe down the decorations with vinegar, and if I do this, will the inverts survive with no filtration/water flow while everything dries? Also, would that restart my fallow clock? I've already lost my 2 Clowns and this has been very stressful for me and my fish. Ich is definitely a beast! TYIA! I appreciate your guidance!

 

[gobble]

Given this development and the fact that it seems pretty common that ich returns after a proper fallow period, is the better option removing coral and inverts from the display and killing the ich by going hyposalinity? It seems like this might have a better chance of success then a fallow period?

 

[chicago]

Hypo is a whole other issue. I did that exact thing three years ago and I am still getting my tank back up and running. Hypo is going to kill a lot of other stuff.

 

[gobble]

I've done two fallow periods now. Both longer than 76 days. I've followed all the rules and both fallow periods have failed. My QT was in the basement, nowhere near my display and I shared nothing between the QT and display. This last time ich came back after a couple months and I've added NOTHING to the tank the last couple months. I have 9 tangs in the tank and all have ich, some worse than others. I'm guessing if I just leave them they will start to really suffer.

What can I do besides destroying my tank a third time to take them all out and do another 3 month fallow period which won't work?

 

[Cell]

Shared nothing, not even the same pipette for your refractometer or water testing? Never had your hands damp from one tank and touched the other? Never fed from same cup of thawed food? There are just so many little things that could cause cross contamination.

 

[Lowell Lemon]

It is like a bad Sci-Fy movie reading this thread. How in the world do fish survive in the wild in such "dirty" conditions? How in the world are you going to manage a completely sterile QT and then DT that includes lifeforms on the rocks, corals, and other inverts? How to target and kill only those things on the fish without damage to the fish itself? How not to create treatment resistant bacteria and other organisms? Just some questions that beg for different answers.

 

[gobble]

I think in the wild the parasites don't multiply in a sealed system. The ocean is large and when the ich drops off others might not be there to immediately re-attach.

I was extremely careful about contamination this time around having failed the first time. Different nets, foods, water buckets, filters, etc. Something could have snuck through but I'd be surprised.

 

[Cell]

It is like a bad Sci-Fy movie reading this thread. How in the world do fish survive in the wild in such "dirty" conditions? How in the world are you going to manage a completely sterile QT and then DT that includes lifeforms on the rocks, corals, and other inverts? How to target and kill only those things on the fish without damage to the fish itself? How not to create treatment resistant bacteria and other organisms? Just some questions that beg for different answers.

Well the ocean is quite a bit bigger tank than our home aquariums.

 

[Lowell Lemon]

Well the ocean is quite a bit bigger tank than our home aquariums.

"A liter of seawater typically contains at least 10 billion microbes and 100 billion viruses the vast majority remain unidentified and uncharacterized." The Scientist Magazine, June 30, 2013.

So you were saying what?

I will lay dollars to donuts the home aquarium has no where near that level based on recent studies here on R2R. Many viruses attack bacteria causing the bacteria to rupture and spill it's contents into the water which is theorized to be part of the food Web for corals and other filter feeders.

Nature has ways of providing for fish and inverts that preclude a QT tank.

 

[Big G]

I've done two fallow periods now. Both longer than 76 days. I've followed all the rules and both fallow periods have failed. My QT was in the basement, nowhere near my display and I shared nothing between the QT and display. This last time ich came back after a couple months and I've added NOTHING to the tank the last couple months. I have 9 tangs in the tank and all have ich, some worse than others. I'm guessing if I just leave them they will start to really suffer.

What can I do besides destroying my tank a third time to take them all out and do another 3 month fallow period which won't work?

Assuming you are correct and the QT was absolutely prefect, are you sure it is Ich that is returning? Might want to read this thread. I know it's focusing on Hippo tangs, but might be worth pondering. Doing a scrape and a gram stain might be helpful, maybe:

Rescue Hippo Tang with spots

Hey everyone, hoping some disease expert here can help ID this! I rescued a hippo tang 5 months ago, she had been in a 29 gallon for 8+ years. We had to rehab her through our system of tanks as she learned to swim, eat food other than brine, and handle current. She’s made it up to our 180 gal...

www.reef2reef.com

 

[moncheng]

> Only use filtration with an open top (like a sump), and avoid canister filters and other filters which may contain anaerobic regions.

@Humblefish , does that mean a hang on back filter (like seachem tidal) with the lid opened would be fine ? im going fallow soon (just need to catch my last fish lawnmower blenny... a pain to catch) but i will still have CUC and coral that i need to feed so ideally i would still need some mechanical filteration, thus the question.

 

[areefer01]

> Only use filtration with an open top (like a sump), and avoid canister filters and other filters which may contain anaerobic regions.

@Humblefish , does that mean a hang on back filter (like seachem tidal) with the lid opened would be fine ? im going fallow soon (just need to catch my last fish lawnmower blenny... a pain to catch) but i will still have CUC and coral that i need to feed so ideally i would still need some mechanical filteration, thus the question.

He no longer posts here. If you do a search on the name you will find out his active location.

 

[MnFish1]

> Only use filtration with an open top (like a sump), and avoid canister filters and other filters which may contain anaerobic regions.

@Humblefish , does that mean a hang on back filter (like seachem tidal) with the lid opened would be fine ? im going fallow soon (just need to catch my last fish lawnmower blenny... a pain to catch) but i will still have CUC and coral that i need to feed so ideally i would still need some mechanical filteration, thus the question.

The answer is that anaerobic - like the 76 day fallow period - is somewhat 'theoretical'. 76 days comes from a study in the 1990s by burgess - who found 1 strain survived that long - out of many. The Anaerobic information also comes from a more recent (to my recollection) - study. Will Ask @Jay Hemdal. My impression - is that there are LOTS of anaerobic areas in every tank - which would cause more of a risk than a canister filter

 

[Shooter6]

The answer is that anaerobic - like the 76 day fallow period - is somewhat 'theoretical'. 76 days comes from a study in the 1990s by burgess - who found 1 strain survived that long - out of many. The Anaerobic information also comes from a more recent (to my recollection) - study. Will Ask @Jay Hemdal. My impression - is that there are LOTS of anaerobic areas in every tank - which would cause more of a risk than a canister filter

Agreed, the issue with anaerobic areas in a filter vs tank is this in my opinion.
Anaerobic conditions cause the eggs to enter a hybranation state. Until they are returned to aerobic conditions.
Anaerobic areas in the tank are not going to be accessible to the parasites. Even when they are in the egg case state, they will not penetrate into the rock. Unless you have a deep sandbed there won't be many other areas that are anaerobic in the display. The chances of the egg case getting deep enough into the sand to be in anaerobic conditions is very miniscule.

Even less likely they will be brought back to aerobic conditions without being siphoned out.

A filter that has aerobic conditions on the other hand will have a high probability of eventually passing the egg case through the anaerobic area and back into the tank via flow.

 

[MnFish1]

Agreed, the issue with anaerobic areas in a filter vs tank is this in my opinion.
Anaerobic conditions cause the eggs to enter a hybranation state. Until they are returned to aerobic conditions.
Anaerobic areas in the tank are not going to be accessible to the parasites. Even when they are in the egg case state, they will not penetrate into the rock. Unless you have a deep sandbed there won't be many other areas that are anaerobic in the display. The chances of the egg case getting deep enough into the sand to be in anaerobic conditions is very miniscule.

Even less likely they will be brought back to aerobic conditions without being siphoned out.

A filter that has aerobic conditions on the other hand will have a high probability of eventually passing the egg case through the anaerobic area and back into the tank via flow.

I'm going to disagree - by definition. If the filter that has aerobic conditions - passes water through the anaerobic area - the anaerobic area becomes aerobic. Unless I'm misunderstanding what you're saying. Now - on the other hand - if you had a deep sand bed - that allowed Cryptocaryon into an anaerobic area - and that subsequent area was 'stirred up' - that I could see

 

[Shooter6]

I'm going to disagree - by definition. If the filter that has aerobic conditions - passes water through the anaerobic area - the anaerobic area becomes aerobic. Unless I'm misunderstanding what you're saying. Now - on the other hand - if you had a deep sand bed - that allowed Cryptocaryon into an anaerobic area - and that subsequent area was 'stirred up' - that I could see

There's filters that pass aerobic water through at a slow speed. Bacteria use up the oxygen, turning it into anaerobic water.

No in canister filters, buildup in the filter media can cause pockets af anaerobic areas, that later break down and become free flowing aka aerobic, or after a back washing become aerobic.

 

[MnFish1]

There's filters that pass aerobic water through at a slow speed. Bacteria use up the oxygen, turning it into anaerobic water.

No in canister filters, buildup in the filter media can cause pockets af anaerobic areas, that later break down and become free flowing aka aerobic, or after a back washing become aerobic.

I thought the question was - will CI live in a canister filter - in an anaerobic area. My answer - when the filter is cleaned - if cleaned 'thoroughly' - not rinsed. No. My answer also - even IF there was an anaerobic area - the chance of CI living is extremely small - as compared to the millions of anaerobic areas in a tank.

As to the other filters yes - but - frankly - its the same as upsetting a sand bed - and - I think we all know how many people have reported a CI outbreak after moving rock work, etc - with no new additions. So - in other words - its possible in multiple ways. I would not worry about a canister filter thats cleaned regularly.

 

[Shooter6]

I thought the question was - will CI live in a canister filter - in an anaerobic area. My answer - when the filter is cleaned - if cleaned 'thoroughly' - not rinsed. No. My answer also - even IF there was an anaerobic area - the chance of CI living is extremely small - as compared to the millions of anaerobic areas in a tank.

As to the other filters yes - but - frankly - its the same as upsetting a sand bed - and - I think we all know how many people have reported a CI outbreak after moving rock work, etc - with no new additions. So - in other words - its possible in multiple ways. I would not worry about a canister filter thats cleaned regularly.

Ci? I'm not sure what your calling ci. As for ich and velvet, which are what fallow is a treatment for, moving rocks will only trigger outbreaks due to stress, not actual release of the parasites.

 

[MnFish1]

Ci? I'm not sure what your calling ci. As for ich and velvet, which are what fallow is a treatment for, moving rocks will only trigger outbreaks due to stress, not actual release of the parasites.

CI - is cryptcaryon irritans (CI) - Ich. There is no such thing (per se) as 'ich' in a saltwater tank - which is the abbreviation for a freshwater organism (Ichthyophthirius multifiliis).

 

[MnFish1]

Ci? I'm not sure what your calling ci. As for ich and velvet, which are what fallow is a treatment for, moving rocks will only trigger outbreaks due to stress, not actual release of the parasites.

Wait - lets back up - do you not think there are anaerobic areas in sand and under rocks that haven't been moved for months? The whole point of the discussion is that CI can live longer in anaerobic areas. There are tons of those areas in every tank and sump.