Bioremediation - Can brine shrimp stop Velvet?

[MnFish1]

It is ultimately immunity which makes this work - but immunity waxes and wanes - it is also a mature tank with a matrix of ciliate predators, sufficient dilution through good filtration and flow which makes mature tanks resistant to sudden blooms sufficient to prove lethal to its residents as it is the sudden bloom that kills.

Its a myth that you have to eliminate ich and velvet from your systems or all you fish will suffer and die and its based on misapplication of the data from very good studies. What this leads to is to cumbersome husbandry practices, sub-optimal treatment of fish and frustration on the part of hobbyists.

We have adopted the practice of seeding tanks with bacteria as part of the cycle. Could we not do the same for the benthic predators of some of our most commonly encountered ciliate parasites? I don't think its far fetched. Thank god for bats!

Which immunity waxes and wanes?
If your fish is immune - you don't have to eliminate velvet or CI from your tank - but if you are adding fish that are not immune - you might have a problem or? IMHO - you can be successful with a QT'd tank (just like Bill Gates is trying to eliminate Malaria) or The WHO is trying to eliminate small pox. They are not introducing parasites, etc into communities to build immunity. Likewise - you can have a successful tank without QT - IMHO you need to use low stocking density and some method of filtration/sterilization (the key being a low stocking density) and high flow.

The filtration part (and the Brine Shrimp part) is interesting - though 'brine shrimp' alone may not be able to eliminate Velvet except in a QT type situation - I think the more 'filter feeders' clams, small inverts, coral - the less likely you will have problems with CI/Velvet. Again - just theory - but backed by several articles - including the one posted by the OP.

 

[robert]

Which immunity waxes and wanes?
If your fish is immune - you don't have to eliminate velvet or CI from your tank - but if you are adding fish that are not immune - you might have a problem or? IMHO - you can be successful with a QT'd tank (just like Bill Gates is trying to eliminate Malaria) or The WHO is trying to eliminate small pox. They are not introducing parasites, etc into communities to build immunity. Likewise - you can have a successful tank without QT - IMHO you need to use low stocking density and some method of filtration/sterilization (the key being a low stocking density) and high flow.

The filtration part (and the Brine Shrimp part) is interesting - though 'brine shrimp' alone may not be able to eliminate Velvet except in a QT type situation - I think the more 'filter feeders' clams, small inverts, coral - the less likely you will have problems with CI/Velvet. Again - just theory - but backed by several articles - including the one posted by the OP.

A fish exposed to either ich or velvet develops an immunity to the pathogen over a few weeks. If this immune fish is exposed to the ciliate at some later date, the cilate is unable to host the fish and dies. This was shown in the lab as no protomonts drop from the fish. This breaks the parasites life cycle and the ciliate population crashes. This immunity however does not last. If the fish sees no more exposure then it begins to lose its immunity. After six months or so the once immune fish again becomes susceptible to infection. That's what I meant by waxes and wanes.

In a recent study of the fish off the coast of Viet Nam - in the spring most wild fish (90%+) caught harbored ich. This number dropped as summer wore on only to bump up again in the fall.
In an environment where populations blooms of these ciliates is blunted through dilution and predation, these pathogens are rarely fatal to the host fish. Its only in the environment of a new tank where there is not predatatory matrix and little or no dilution that the populations of these pathogens are able to explode before the fishes immune response has time to mount a defense.
This is what allows ich to be fatal in our tanks while being very unlikely on a reef.

QT works, but without sufficient dilution or a predatory matrix, it is a set-up for catastrophe should ich, velvet or one the myriads of other pathogens (most of which are unknown) makes it into the system. Which they will. I like to point out that the GA aquarium practiced QT but even they got ich in their massive display.

Finally, we naively think we understand ich's/velvets life-cycle. We don't. We know how it behaves in the lab, but have little idea how it functions on the reef or in the eco-systems of our tanks. Ich for instance can go dormant...its how ich persists season over season in the wild...recently we learned that hypoxic environments can put it to sleep. Burgess never saw this. We also have never seen sexual reproduction in this parasite - without it sell lines could not persist beyond 30-50 generations - so it happens - we just don't yet know how, when or where.

 

[MnFish1]

A fish exposed to either ich or velvet develops an immunity to the pathogen over a few weeks. If this immune fish is exposed to the ciliate at some later date, the cilate is unable to host the fish and dies. This was shown in the lab as no protomonts drop from the fish. This breaks the parasites life cycle and the ciliate population crashes. This immunity however does not last. If the fish sees no more exposure then it begins to lose its immunity. After six months or so the once immune fish again becomes susceptible to infection. That's what I meant by waxes and wanes.

The study you're quoting is interpreted as saying that the fish becomes susceptible again - but that's not what the study said/says. The last group of fish in the study was sacrificed at 6 months. None were studied longer than 6 months - so its completely unknown whether immunity just drops slightly or completely - or after 6 months - nor is it known when that happens (if it does). What is interesting in the study - is that in the abstract it says 'very few fish developed full immunity' - i.e. were still harboring torments (though far far fewer than the controls).

At 6 months the fish had slightly higher numbers of parasites than at 3 months - but still far far less than the control fish (I believe at 6 months the study group had 1 percent of the torments that the control group did).

I have posted this on another thread (the raw data - but cannot find it on my computer).

In the vietnam study - the infection rate did fluctuate - but its not like it went to zero during the warmer seasons. The difrerence was that CI is not as prevalent at higher temperatures in the summer.

So - to me my reading of these - it suggests that Immunity 'helps' and various environmental factors may play a role - but I'm not sure either one say much about whether QT is good or bad.

Back to the original topic - I think filter feeders (and natural predators of CI) are probably playing a role in more established tanks (ie controlling CI). I do not think its necessarily a good idea to 'add parasites' to the tank as we would beneficial bacteria. IMHO - buy fish from a trusted source, try to add several fish from that source at one time as compared to 1 every 2 weeks. Dont overstock and CI is much less of a problem.

The problem to me of no QT is not CI - its velvet. PS - did the large aquarium that was QTing stop QTing after CI was found - or did they troubleshoot the problem and fix whatever went wrong in their process.

 

[robert]

That would be the Burgess thesis...I have it so no need to dig it up.

They measured the the protomonts that dropped from exposed fish after exposure at monthly intervals over the course of six months - A very high initial drop rate fell to 0 and began to tick up again after six months. The six month number was still very low relative to the initial rates so they interpreted that as a indication that immunity had begun to wane. This is in strong agreement with my own experience running continuous DE filtration and the observation of reinfection of previously exposed fish.

"Duration of immunological memory seemed not to be dependent on infectious doses with the primary exposure. High levels of immobilization activity and specific antibodies against the 28 kD antigen were produced 21 days after initial exposure at all dose levels. However, the apparent decreases in immobilization titres and the specific antibody levels were observed in fish that were not reexposed to C. irritans for 49 days after the initial exposure (Fig. 7). The decline in immobilization titres and the specific antibody level in those fish probably resulted from a loss of antigenic stimulus. Very similar results were obtained by Luo et al. (2007) using grouper (Epinephelus coioides)." Parasitol Res (2012) 110:363–372

"In the vietnam study - the infection rate did fluctuate - but its not like it went to zero during the warmer seasons. The difrerence was that CI is not as prevalent at higher temperatures in the summer. "

Nothing I have encountered would suggest that warmer temperatures (short of 94F) alter CI prevalence or infectivity. My interpretation would be that high rate of infection seen in the spring resulted in a reduced infectivity rate due to the fishes immunological response. This in turn leads to a drop in transmission over the summer until immunologic memory of the population waned in the fall resulting in the seasonal up-tick.

"I do not think its necessarily a good idea to 'add parasites' to the tank as we would beneficial bacteria"

Neither do I and if somehow you got that from what I wrote, it was unintentional. I was suggesting the seeding of a predatory matrix to blunt blooms of parasite ciliates.

 

[MnFish1]

That would be the Burgess thesis...I have it so no need to dig it up.

They measured the the protomonts that dropped from exposed fish after exposure at monthly intervals over the course of six months - A very high initial drop rate fell to 0 and began to tick up again after six months. The six month number was still very low relative to the initial rates so they interpreted that as a indication that immunity had begun to wane. This is in strong agreement with my own experience running continuous DE filtration and the observation of reinfection of previously exposed fish.

"Duration of immunological memory seemed not to be dependent on infectious doses with the primary exposure. High levels of immobilization activity and specific antibodies against the 28 kD antigen were produced 21 days after initial exposure at all dose levels. However, the apparent decreases in immobilization titres and the specific antibody levels were observed in fish that were not reexposed to C. irritans for 49 days after the initial exposure (Fig. 7). The decline in immobilization titres and the specific antibody level in those fish probably resulted from a loss of antigenic stimulus. Very similar results were obtained by Luo et al. (2007) using grouper (Epinephelus coioides)." Parasitol Res (2012) 110:363–372

"In the vietnam study - the infection rate did fluctuate - but its not like it went to zero during the warmer seasons. The difrerence was that CI is not as prevalent at higher temperatures in the summer. "

Nothing I have encountered would suggest that warmer temperatures (short of 94F) alter CI prevalence or infectivity. My interpretation would be that high rate of infection seen in the spring resulted in a reduced infectivity rate due to the fishes immunological response. This in turn leads to a drop in transmission over the summer until immunologic memory of the population waned in the fall resulting in the seasonal up-tick.

"I do not think its necessarily a good idea to 'add parasites' to the tank as we would beneficial bacteria"

Neither do I and if somehow you got that from what I wrote, it was unintentional. I was suggesting the seeding of a predatory matrix to blunt blooms of parasite ciliates.

Yep - thats the study . The point being everyone says 'immunity to CI goes away after 6 months' - there is no evidence to suggest that.

And its in the conclusion/discussion (I believe) that at higher temperatures (34C) no CI was found (that was from a different study) - but they referenced it to suggest why they saw lower numbers in the summer months.

And yes - I misread this sentence from you: Could we not do the same for the benthic predators of some of our most commonly encountered ciliate parasites? I don't think its far fetched.

I thought you were suggesting (as several others have on other threads) that parasites be added to the tank to 'maintain' an immunity that never may have been lost.

BTW - I guess I wonder - does lack of antibody imply lack of 'immunity'... For example - If I had a tetanus shot 5 years ago - I may have trivial anti tetanus antibody in my serum - but if I got a tetanus infection - it would be rapidly increased (fish may be different)?

Intersting discussion

 

[robert]

I think we're reading the same studies...34C ~= 94F...

"The point being everyone says 'immunity to CI goes away after 6 months' - there is no evidence to suggest that. "

I think there is...Fish have a primitive immune system compared to mammals. They rely heavily on innate immunity and although they can and do develop specific or adaptive immune responses, it is slow and takes a sustained exposure to an antigen over a prolonged period of time. There is a report of a tomato clown for instance which was exposed to velvet in small quantities which developed strong immunologic memory to velvet - but it was something that was done in the lab over many months. Its is this reliance on innate immunity which makes creating vaccines in fish such a challenge. Its easy to get a the fish to mount a response, its quite another to get that response to last. Twelve months seems to be the outside limit although I've seen reports of 24 months it doesn't seem to be a robust result. They're studying adjuvants to try and extend these durations...

Finally...If you think carefully about the Viet Nam Study where ~90% of fish in the spring were found to host CI. If the immunity to CI persisted 12 months or beyond how would this be possible? - how could you explain it? Did they only look at fish that were less than 1 year old?

Your correct in correcting those who claim immunity to CI lasts only up to six months - the studies didn't show that but they did show that it begins to wane after six months. Is there another which show differently? Is there any evidence which suggests it lasts substantially longer?

Fish are different. Its probably not correct to apply what we know about mammalian immunity to fish...

 

[MnFish1]

I think there is...Fish have a primitive immune system compared to mammals. They rely heavily on innate immunity and although the can and do develop specific or adaptive immune responses, it is slow and takes a sustained exposure to an antigen over a prolonged period of time. There is a report of a tomato clown for instance which was exposed to velvet in small quantities which developed strong immunologic memory to velvet - but it was something that was done in the lab over many months. Its is this reliance on innate immunity which makes creating vaccines in fish such a challenge. Its easy to get a the fish to mount a response, its quite another to get that response to last. Twelve months seems to be the outside limit although I've seen reports of 24 months it doesn't seem to be a robust result. They're studying adjuvants to try and extend these durations...

I agree that fish have a different immune system. Im not sure that the chart showing the immune system is 'different' says much - but an interesting summary. The only issue I have with the chart is what does 'low' and what does 'high' defined by. It is mammals compared to fish? What antigen was used? But either way - I'm not sure its completely understood how long and how strong the immune memory to CI lasts or how it works in fish.

Finally...If you think carefully about the Viet Nam Study where ~90% of fish in the spring were found to host CI. If the immunity to CI persisted 12 months or beyond how would this be possible? - how could you explain it? Did they only look at fish that were less than 1 year old?

Yet - if its the case that as long as fish are continuously exposed to CI - that the fish remain immune - how are any of them infected since there is CI in the water throughout the year? To answer what you're saying - though - perhaps the fish in Vietnam had 'subclinical' i.e. low-levels of CI - as compared to active infection because they were immune (i.e. were carriers)? BTW - its not like they examined the exact same(individual) fish in summer and spring - and the percentages varied in different species. The major weakness in the study is that they did not repeat it the next year or year after - so there is no way to determine anything except that in 2016 - these were the percentages in spring and summer.

 

[robert]

I agree that fish have a different immune system. Im not sure that the chart showing the immune system is 'different' says much - but an interesting summary. The only issue I have with the chart is what does 'low' and what does 'high' defined by. It is mammals compared to fish? What antigen was used? But either way - I'm not sure its completely understood how long and how strong the immune memory to CI lasts or how it works in fish.

Yes mammals as compared to fish. I posted it to give a frame of reference only in response to your prior question. In general when compared to mammals the fish immune system has low antibody specificity. Antibodies develop slower, antigenic memory is weak and antigenic specificity does not mature - become more specific with time. This was not intended as a direct answer to your question regarding tetanus - just as a caution to applying what you know about mammalian immunity too liberally to fish.

Yet - if its the case that as long as fish are continuously exposed to CI - that the fish remain immune - how are any of them infected since there is CI in the water throughout the year? To answer what you're saying - though - perhaps the fish in Vietnam had 'subclinical' i.e. low-levels of CI - as compared to active infection because they were immune (i.e. were carriers)? BTW - its not like they examined the exact same(individual) fish in summer and spring - and the percentages varied in different species. The major weakness in the study is that they did not repeat it the next year or year after - so there is no way to determine anything except that in 2016 - these were the percentages in spring and summer.

The Viet Nam study confirms what has been observed at other reefs. The studies over the barrier reef have found similar numbers. Its a data point. I could come up with numerous hypothetical explanations to explain the data. Maybe its a result of fish behavior, or dietary differences. Maybe its the water temperature, or the development of termoclines in summer.
In the end it really doesn't matter. The environment on the reef does not support the degree of bloom we see in the lab or the "new" aquarium. Why?

If you introduce 100 trophonts into your system on a fish and at the end of the first cycle your fish are carrying less than 100 the infestation will fizzle, more and it will increase. On the reef this fluctuates slightly over the season but it hovers around the replacement ratio of 1:1. It has to by definition. Burgess guessed it went to about a 1:10 ratio in our tanks - meaning an explosive bloom.

The premise of this thread was to discuss the idea that we could use bioremediation techniques to shift the balance (ratio) to the extent that this, coupled with the fishes immunity, could be enough to bring the ratio back to or below the 1:1 ratio. Do you doubt that fish develop immunity to CI or that developing immunity (perfect or not) helps produce that shift if we were successful in blunting a bloom?

In the end its a balancing act and numbers game. A favorable balance avoids the bloom and could indeed extinguish the parasite from the system. Could the parasite avoid the extinction consequences of a negative balance - yes - and it is theorized that the variable duration in encystment interval (7-11 weeks) is one part of natures strategy to ensure that a transient negative ratio does not wipe out the parasite. Another is the recent discovery that CI can lay dormant for extended periods in hypoxic zones.

But should the tank end up in an extended "subclinical" state of mild infection, bouncing around the 1:1 replacement ratio, then senescence appears to limit the number of generations a single strain can persist and you would still end up with a parasite free tank. If you want to get into murky science - senescence would be it.

 

[robert]

Thanks for the questions by the way - the whole enjoyment of posting an idea is to have it challenged with good questions and alternate interpretations, but at the end of the day theory has to meet practice.

How about this idea for implementing the tank transfer method without the transfer.

Set up a tank, divided in depth by egg-crate or another suitable barrier such that the fish cannot come closer than ~6" to the bottom. Below the egg-crate have a population of peppermint shrimp to feed on the encysted stages of CI - the protomonts and tomonts. Down with the shrimp place a 5uM string/sediment filter attached to a pump to catch trophonts as they hatch. The clean output from the pump goes to the top of the tank so that the flow is generally downward. Feed sufficiently for the fish but avoid feeding the peppermints as much as possible.

Maybe put an infected fish in such a tank with a couple black mollies to visualize/measure the effectiveness or lack thereof.

Could such an arrangement eliminate CI? What do you think? What improvements would you make and why would you make them?

 

[Gareth elliott]

Would the filter not also catch the brine shrimp?

Would a simple sponge filter be more advantageous to the sustainability of brine shrimp populations?


Perhaps instead of relying on the two species of shrimp entirely, couple the method with

Regularly scheduled water changes instead of a transfer.
that during refilling the brine shrimp populations are added back in?

This would be similar to treatment protocols for subadult Lernaea, except instead of chemical treatment during the time between population dilutions you are using the brine shrimp to control.

Something like:
After tank is cycled
Day 1 add fish, peppermint shrimp and brine shrimp.
Day 2 take sample of water to count brine shrimp in x volume on a microscope to gauge predation numbers over a day and adjust how much to add each and how often.
Add more brine if population has dropped too low, now known as Step B
Day 3 add infected fish and step B.
Day 4 Take another sample as more predation with another fish likely. Step B

Day 5 50% wc and Step B with additional shrimp to replace those removed during pwc.

Day 6 swab black mollies check for parasites under scope. Step B.
Continued run of similar days after this
....
Also have a separate tank setup without the shrimp using the same fish stocking numbers without any shrimp but using the same wc schedule as a control.

 

[MnFish1]

If you introduce 100 trophonts into your system on a fish and at the end of the first cycle your fish are carrying less than 100 the infestation will fizzle, more and it will increase. On the reef this fluctuates slightly over the season but it hovers around the replacement ratio of 1:1. It has to by definition. Burgess guessed it went to about a 1:10 ratio in our tanks - meaning an explosive bloom.

The premise of this thread was to discuss the idea that we could use bioremediation techniques to shift the balance (ratio) to the extent that this, coupled with the fishes immunity, could be enough to bring the ratio back to or below the 1:1 ratio. Do you doubt that fish develop immunity to CI or that developing immunity (perfect or not) helps produce that shift if we were successful in blunting a bloom?

I agree - I already said I think predation of CI and other parasites somewhat better in check than if they weren't there. I do not doubt that fish develop immunity - and I think it may produce the shift. But - in such a tank - I don't think the immunity to CI waxes and wanes in the manner you were saying earlier

 

[Scott Campbell]

A question for Robert & MnFish - how does fish immunity to a parasite actually work? To return to the mosquito comparison - I can understand how exposure to repeated mosquito bites can lessen the effect of a bite. I have noticed this myself over the years. The mosquito bites are not as itchy or bothersome after years of being bitten. I can also understand that ingesting certain foods (like bananas perhaps) might make you a less appealing target for a mosquito. But it seems as if you are saying fish can simply resist the parasite from even attaching. Sort of like developing skin of armor and becoming impervious to all mosquito bites. That seems like quite a strange immunity to develop. Obviously it happens. I just don't understand the mechanism behind it.

 

[Gareth elliott]

https://www.ncbi.nlm.nih.gov/m/pubmed/18783835/

As far as studies i have read they are not entirely sure yet. But mnfish has better access to studies than i do. But this is common in immunology and pharmacology where they test a theory with a drug they develop and if works assume it works because of the hypothesis they were testing or perhaps one that comes during clinical tests. Example would be virtually every psychotropic on the market. Where if you read the literature behind them some where will be a “we think it works for because of this mechanism”

 

[MnFish1]

A question for Robert & MnFish - how does fish immunity to a parasite actually work? To return to the mosquito comparison - I can understand how exposure to repeated mosquito bites can lessen the effect of a bite. I have noticed this myself over the years. The mosquito bites are not as itchy or bothersome after years of being bitten. I can also understand that ingesting certain foods (like bananas perhaps) might make you a less appealing target for a mosquito. But it seems as if you are saying fish can simply resist the parasite from even attaching. Sort of like developing skin of armor and becoming impervious to all mosquito bites. That seems like quite a strange immunity to develop. Obviously it happens. I just don't understand the mechanism behind it.

The first part is the various non-specific defenses in/on the mucus and the mucus itself. (on the skin, gills, etc) - then after infection there are antibodies and cells that recognize the 'foreigner' and try to kill that specific 'foreigner'. It is thought that after 6 months this memory of the foreigner drops - whether it drops to zero I would doubt - my guess is that anytime a fish is rexposed/reinfected - the memory comes back. Here is a summary of the various parts'
EDIT - sorry wrong article: https://link.springer.com/chapter/10.1007/978-3-319-76768-0_19

 

[Scott Campbell]

The first part is the various non-specific defenses in/on the mucus and the mucus itself. (on the skin, gills, etc) - then after infection there are antibodies and cells that recognize the 'foreigner' and try to kill that specific 'foreigner'. It is thought that after 6 months this memory of the foreigner drops - whether it drops to zero I would doubt - my guess is that anytime a fish is rexposed/reinfected - the memory comes back. Here is a summary of the various parts'
EDIT - sorry wrong article: https://link.springer.com/chapter/10.1007/978-3-319-76768-0_19

Adaptive skin. That is wild. Thanks!!

 

[robert]

Watch how you interpret abstracts, for example:

"The dinoflagellate Amyloodinium ocellatum, which causes amyloodiniosis or “marine velvet disease,” is one of the most serious ectoparasitic diseases affecting warmwater marine fish culture worldwide. We demonstrated that tomato clownfish Amphiprion frenatus can develop strong immunity to infection following repeated nonlethal parasitic challenges. The protective response is long‐lived and directed against the trophont stage of the parasite."​

What does long-lived mean? From the full text:

"This report describes the development of immunity by the tomato clownfish to lethal challenge by Amyloodinium ocellatum and the persistence of immunity for several months in the absence of antigenic stimulation. Our data indicate that the protective immune response is directed against the trophont stage of the parasite."​

Can a fish that had CI or velvet and recover, succumb to subsequent infection? I've seen it numerous times. I think we all have.

So, persistent exposure -> persistent immunity. Absence of exposure -> dimunation of immunity. Waxes and wanes. Its the nature of the innate immune response, acts quickly, starts building within a week - reaches maximal potential in ~30 days. Starts to wane at 6 months. Lasts up to a year, maybe two in exceptional circumstances. Its why we have no vaccine against any fish parasite.

I've seen nothing that indicates that prior exposure in any way "primes the response" to subsequent infection with respect to CI or velvet. I would appreciate a cite, even if not specific, which suggests such an action exists in fish - or - is this conjecture? - which is fine.