lower salinity in fish only tanks ??

[Crashjack]

Unfortunately, I don't have access to this article any longer but scientific studies have been done showing reduces parasitic reproduction at lower salinities.
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2761.1979.tb00146.x/full

If I'm reading the abstract correctly and have done my math right, it is basically saying that at 77-86 deg. F, 30% of Cryptocaryon irritans tomonts ruptured at a salinity of 1.007 s.g. (assumes 1.0265 NSW and no temperature correction). Of course, this only applies to one particular parasite, and 1.007 s.g. is pretty low. Apparently, one could also run a tank at 99 deg F or 68 deg F while running around 1.013 s.g. and rupture 50% of tomonts. I guess if all other considerations for fish are ignored at the expense of killing up to 50% of Cryptocaryon irritans tomonts, we have our answer.

 

[Crashjack]

No the proof is in the pudding because I’v done it, countless times, and it works. That’s why the industry and hobbyists alike widely use this practice. Or maybe everyone does it and continues to because it doesn’t work. And it’s some big cover up to save a few pennies on salt.

I'm not claiming that you can't successfully keep fish at salinities lower than NSW... a lot of people do. I'm claiming it is no better to keep fish at salinities lower than NSW and that the "best" salinity for most fish is likely the salinity of the environment they came from.

 

[Forsaken77]

What exactly are we considering lower salinity here? Hyposalinity range, or 1.022 range?

And while fish adapt to where they're from, they also osmoregulate to the conditions they're in.

Having salinity too low on a constant basis will cause organ failure over time, or so I've read in an old publication.

 

[theMeat]

What exactly are we considering lower salinity here? Hyposalinity range, or 1.022 range?.

Can’t speak for anyone but think between 1.016 - 1.020

 

[Brew12]

If I'm reading the abstract correctly and have done my math right, it is basically saying that at 77-86 deg. F, 30% of Cryptocaryon irritans tomonts ruptured at a salinity of 1.007 s.g. (assumes 1.0265 NSW and no temperature correction). Of course, this only applies to one particular parasite, and 1.007 s.g. is pretty low. Apparently, one could also run a tank at 99 deg F or 68 deg F while running around 1.013 s.g. and rupture 50% of tomonts. I guess if all other considerations for fish are ignored at the expense of killing up to 50% of Cryptocaryon irritans tomonts, we have our answer.

I wasn't sure if you would have full access to the article. I used to through a co-worker (work paid for his scientific database access). The abstract only hints at the relevant part.

"However, none of the cysts developed normally at these dilutions."

If you are really interested in this subject, the paper is worth paying for. The rupturing tomont data may be interesting but isn't too important since it never reaches 100%. Hyposalinity works on some strains of Crypto because none of the cysts developed normally. The paper documents how, for the particular strain they studied, cycst development was negatively impacted as salinity dilution increased. This is the logic behind running lower salinity.

Would I do it in a fish only aquarium? No. As you point out, it doesn't impact every parasite we worry about. It doesn't even impact every strain of Crypto. I thought you were seriously asking for scientific studies showing that lowering salinity impacts parasite reproduction.

 

[theMeat]

If I'm reading the abstract correctly and have done my math right, it is basically saying that at 77-86 deg. F, 30% of Cryptocaryon irritans tomonts ruptured at a salinity of 1.007 s.g. (assumes 1.0265 NSW and no temperature correction). Of course, this only applies to one particular parasite, and 1.007 s.g. is pretty low. Apparently, one could also run a tank at 99 deg F or 68 deg F while running around 1.013 s.g. and rupture 50% of tomonts. I guess if all other considerations for fish are ignored at the expense of killing up to 50% of Cryptocaryon irritans tomonts, we have our answer.

No one is claiming it is a cure, or will rid the tank of all unwanteds. It simply, easily makes things less conducive for most parasites to thrive. You won’t kill them all but reduce population, which is often the difference between loosing your fish and not. Plus, it lowers stress for fish. You wouldn’t know this because you never did it. So while you look for your scientific proof, you might want to find a fish psychologist too. In the meantime, anyone else worth one’s salt in this hobby, industry will continue to use what helps.
Whether a fish dies of old age at 14 years instead of 15 is pretty hard to figure, and impossible if it dies from a parasite infestation first

 

[Yuki Rihwa]

Well, I just want to remind that all the fish species we having now now actually live right at the coral reef in the wild and majority of these fish available for sale in any LFS are wild caught, so lower salinity will help combat parasite but it doesn't meant good for the fish, you doing something that meant to favor on your side not the fishes side, even with FOWLR tank I still keep my water condition near perfect like I'm keeping SPS/LPS, it's your tank do whatever you like, it's just my 2 cents!

 

[Crashjack]

I wasn't sure if you would have full access to the article. I used to through a co-worker (work paid for his scientific database access). The abstract only hints at the relevant part.

"However, none of the cysts developed normally at these dilutions."

If you are really interested in this subject, the paper is worth paying for. The rupturing tomont data may be interesting but isn't too important since it never reaches 100%. Hyposalinity works on some strains of Crypto because none of the cysts developed normally. The paper documents how, for the particular strain they studied, cycst development was negatively impacted as salinity dilution increased. This is the logic behind running lower salinity.

Would I do it in a fish only aquarium? No. As you point out, it doesn't impact every parasite we worry about. It doesn't even impact every strain of Crypto. I thought you were seriously asking for scientific studies showing that lowering salinity impacts parasite reproduction.

Sorry if I made it sound like I was looking for evidence that lower salinity can significantly reduce parasites... it most certainly does at pretty extreme levels (hyposalinity), though it doesn't effect all parasites like we've said. It might even have some effect on some parasites at levels higher than hyposalinity but lower salinity long term could also cause stress or effect a fish's immunity, making it more susceptible to infection in the first place... we really don't know.

My argument is that lower salinity isn't better for the health and well-being of saltwater fish unless it is being used as a treatment (i.e. hyposalinity and freshwater dips). Keeping one's salinity at say 1.020 long term (that's well below NSW), very well might not hurt his or her fish, but it isn't better for the health and well-being of his/her fish. If it is, I want to see the science that backs that up.

 

[Brew12]

Sorry if I made it sound like I was looking for evidence that lower salinity can significantly reduce parasites... it most certainly does at pretty extreme levels (hyposalinity), though it doesn't effect all parasites like we've said. It might even have some effect on some parasites at levels higher than hyposalinity but lower salinity long term could also cause stress or effect a fish's immunity, making it more susceptible to infection in the first place... we really don't know.

My argument is that lower salinity isn't better for the health and well-being of saltwater fish unless it is being used as a treatment (i.e. hyposalinity and freshwater dips). Keeping one's salinity at say 1.020 long term (that's well below NSW), very well might not hurt his or her fish, but it isn't better for the health and well-being of his/her fish. If it is, I want to see the science that backs that up.

Ah, I'm with you now. I completely agree with that. The low salinity "may" not hurt but if I were running a fowlr I would maintain as close to natural sea water as possible. I can't say one way or another if it would impact the fish negatively but I would default to trying to maintain natural conditions.

 

[Crashjack]

The low salinity "may" not hurt but if I were running a fowlr I would maintain as close to natural sea water as possible. I can't say one way or another if it would impact the fish negatively but I would default to trying to maintain natural conditions.

Exactly. Without some real science to support maintaining fish at salinities lower than NSW, I would always default to NSW salinities because that is what fish have adapted to and thrived in for eons.

 

[Pacific Island Aquatics]

This is a great discussion topic, thanks to the OP!

Reduced salinity is a useful tool in certain scenarios. Reducing the salinity does reduce osomoregulatory stress, for this reason I will place fish with reduced gill capacity in hyposalinity. A good example is a fish affected with Brooklynella sp., Amyloodinium sp. or Cryptocaryon sp. In the event of a catastrophic infection, extreme hypo can give the fish the respiratory relief it needs for a short term while other treatments are pursued. There is substantial evidence that extreme hyposalinity can signifcantly impact Crypt, however it must be very very low. Going "slightly hypo" has not been documented to reduce Ich, it's all or nothing. The caveat here is that a salinity this low is most certainly adding other unknown physiological stressors on the fish. Hyposalinity does nothing to impact Uronema sp., in fact they seem to reproduce more rapidly at lower salinities (In fact hypersalinity can be effective in suppressing Uronema sp.).

There are documented cases of some Pomacanthids living in extreme hypo salinity for many years, that being said the physiological ramifications are unknown. There seem to be some species that are sensitive to this, and it may result in kidney damage in the long run. I do not know where exactly this value is, however I think that by and large full strength salinity, or close to it, are likely the safest bet for long term health. Diseases such as ich are not typically a real problem, but more of an indicator of an underlying problem in a tank (i.e. nutritional deficiencies, water quality problems, or some underlying stressor). If you are having consistent disease outbreaks, then surely lowering the salinity a little will not be the solution.

 

[Crashjack]

Reduced salinity is a useful tool in certain scenarios. Reducing the salinity does reduce osomoregulatory stress, for this reason I will place fish with reduced gill capacity in hyposalinity.

When I tried to find some scientific support showing advantages of lower salinities for marine fish (salinity lower than natural habitats), I could only find the contrary. One of the claims was that lower salinity reduced metabolic rates. Everything I found stated this wasn't true. This excerpt is from one of the articles I found:

Morgan and Iwama (1991) reviewed the studies on the metabolic responses of several species of fishes from fresh-, brackish-, and saltwater. They concluded that low metabolic rates are most often associated to the water salinity in which the species are most commonly found and, therefore, most physiologically adapted to, at a particular life stage. This seems to be in agreement with the natural environment in which O. hatcheri and O. bonariensis are distributed. Odontesthes hatcheri occurs in rivers that seem to be poor in minerals (Luchini, 1981; Martty, 1992). In contrast, 0 ppt does not seem to be the usual salinity level encountered in the areas inhabited by O. bonariensis. Pampasic lakes are peculiar by the high content of Na, Cl and other elements (Mac Donagh, 1934; Ringuelet et al. , 1967) and this seems to be also the condition of the ground water in this region (Saravia et al., 1987).

Obviously, hyposalinity has treatment benefits associated with parasites. Lower salinity would also allow for "less" osmoregulation, though I don't know about the "less stress" part.

 

[Koi Obsession]

Wow, can everyone just get along here? lolo Ok if you have a fish that has Ich on it The first thing I do is a fresh water dip for 3 to 4 min It stands to reason that parasites don`t do well in lower salt levels ? Less be honest know one in this hobby is concerned about a few dollars saved on a cup of salt? If your running a lower salt level to save a dollar pleas get out of the hobby. I have an 800 with over 100 fish in the system. I keep my salt low for health reasons. My fish are very happy. So please take this with a grain of salt no pun intended. WE all just need to play nice with one another..

 

[JasPR]

For what it’s worth— have been keeping SW fish for 39 years at 1021-1023. For the past 4 I have been keeping the big fish only tank at 1018-1020. I’ve also done the 1/2 dose cupermine + 1016 SG bit with excellent results. Takes care of ich/ odinium nicely with near zero losses. Today I’m running 1019 in the fish only 440 gallon and 1024-25 in my mixed anemone/ fish and all reef coral systems. I use instant ocean in the 440 and crystals in the mixed reef and coral reef tanks

 

[Crashjack]

Wow, can everyone just get along here? WE all just need to play nice with one another..

???

I thought we were playing nice. This is an interesting and much debated topic. Just because everybody doesn't agree doesn't mean people are at each other's throats. That said, if anything I wrote came across as a personal attack, I sincerely apologize. My intent has been only to debate the topic and not to attack anybody or their fishkeeping methods. I'm sorry if my ramblings offended anyone.

 

[chevegan]

???

I thought we were playing nice. This is an interesting and much debated topic. Just because everybody doesn't agree doesn't mean people are at each other's throats. That said, if anything I wrote came across as a personal attack, I sincerely apologize. My intent has been only to debate the topic and not to attack anybody or their fishkeeping methods. I'm sorry if my ramblings offended anyone.

did you read this?
https://www.advancedaquarist.com/2007/6/fish

 

[Crashjack]

I agree that true hyposalinity is an effective method for removing some parasites. No doubt the author of this article is very knowledgeable, but he also seems to be mixing science with anecdotal concepts:

There may be some concern that hyposaline conditions could be stressful to marine teleost fish, or otherwise potentially harmful. While this is true in extreme salinities, studies indicate that this is not the case in more moderate salinities that would be employed in hyposalinity therapy (Wu & Woo, 1983. Woo & Chung, 1995. McDonald & Grosell, 2006).

This doesn't indicate that lower salinities are "better" only that in a lot of circumstances, hyposaline conditions aren't stressful or harmful, at least for relatively short periods of time.

Natural Sea Water is much more saline than the internal fluids of marine fish. Because of this, they expend a considerable amount of energy to reduce the excessive salt load through the process of osmoregulation.

No doubt osmoregulation expends energy. However, everything I could find pointed back to what I posted earlier: Morgan and Iwama (1991) reviewed the studies on the metabolic responses of several species of fishes from fresh-, brackish-, and saltwater. They concluded that low metabolic rates are most often associated to the water salinity in which the species are most commonly found and, therefore, most physiologically adapted to, at a particular life stage.

The kidneys are not the primary site of electrolyte management in marine teleost fish (Stoskopf, 1993). Chloride cells in the gills excrete excess chloride and sodium. “The kidneys of marine fish do play a role in electrolyte excretion; however, there function is more important in the balance of magnesium and sulfate levels and not, as might be assumed, in sodium and chloride elimination” (Stoskopf, 1993).

Though interesting, I don't see where this addresses that lower salinities are "better" for saltwater fish.

The effects of stress caused by capture, transport and handling is a major concern when acclimating fish, especially when they have been bagged for a prolonged period. Stress affects fish in two ways: it produces effects that disrupt or threaten homoestatic equilibrium and it induces adaptive behavioral and physiological responses (Wendelaar Bonga,1997).

The first sentence is anecdotal. Though regarded as true, we can't measure how stressful these conditions are to a fish or how long that stress lasts. The second sentence, I will concede, has scientific basis.

Osmoregulatory dysfunction is closely associated with stress in fish. This is recognized by an increase in osmolarity in saltwater species (Carmicheal et. al, 1984. Robertson et. al, 1988.). This can manifest in the loss of up to ten percent of body weight due to dehydration in one or two days (Sleet & Weber, 1982.). Reducing the salinity gradient between the water and the internal fluids of fish is effective in counteracting osmoregulatory dysfunction and other physiological responses to stress (Johnson & Metcalf, 1982. McDonald & Milligan, 1997.) With marine teleost species, this is accomplished by reducing the salinity of their environment.

Everything but the last sentence has scientific support... following that logic, the last sentence makes sense. However, the "scientific" piece is talking about osmoregulatory dysfunction, not normal osmoregulatory processes. Hence, the argument to use lower salinities to combat stress definitely has merit. The question is, how do we measure the level of stress in a fish or how long that stress lasts? This also ignores the fact that stress might be induced by putting a fish in lower salinity water in the first place... at least if not acclimated to it properly. In other words, if we knew that a fish would maintain a certain level of stress for a certain amount of time, we could conclude that a lower salinity during that time would likely be beneficial to combat dehydration. I don't think we really know the level of stress that shipping causes or how long it lasts. That said, shipping at lower salinities very well might be as safe as shipping at normal salinities.

My point is this... I could take an alligator from a Florida lake and put it in a Canadian lake and say, "The alligator will be better off because its metabolic processes will slow due to the colder climate, making it need less food and enabling it to conserve more energy." This might be true, but knowing that alligators have adapted to and thrive in a Florida environment and climate, there would have to be a LOT of scientific proof that my alligator would be better-off by relocating it to Canada. It is the exact same thing here... these fish have adapted and thrive in the salinities they live in and if that isn't the best environment for them, there has to be a lot of scientific proof to support. What I see out there is mostly anecdotal, and nowhere near enough to convince me that saltwater fish are healthier at salinities lower than from where they came, except when treating for specific parasites.

 

[Ken Roane]

All of the LFS around me run their fish only tanks at a lower salinity to keep parasites at bay.

I notice that your icon picture is a lion fish. Are these fish special to you, I have reason to know?

 

[Ken Roane]

I notice that your icon picture is a lion fish. Are these fish special to you, I have reason to know?

 

[Waters]

I notice that your icon picture is a lion fish. Are these fish special to you, I have reason to know?

I chose that pic strictly because it is my favorite marine fish......I have always liked them but have been unable to keep them due to the high flow in my reef tanks.