julii corys and the "why ?" of salt sensitivity ?

[raglanroad]

http://www.journals.uchicago.edu/doi/abs/10.1086/339216
Greetings Planet Catfish.
Just found this while argue-trolling, don't know if you already have this report.

.. seemed to me that corys might not be more sensitive, vis a vis serum levels or tissue levels or whatnot, but rather they get more of it than oither fish do, out of the same water...?
Dave

[Bas Pels]

following the lead - thank you for the info I read:

Unlike other species with high Km values, the catfish Corydoras julii maintained high rates of Na+ uptake in dilute waters by having a Jmax value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L−1 NaCl, Jmax fell >50%, and Km dropped about 70%. The unusual acclimatory drop in Km may represent a mechanism to ensure high rates of Na+ uptake on return to dilute water.

Thus I would conclude that this Corydoras is able to REGULATE this intake - contrarily to other fishes

However, it would be good te try these experiments with other fishes, amongst which Corydoras, fron white water rivers, before drawing too much conclusions. The found ability might be common to Corydoras, but could olso be slecial to C julii

The sensitivity towards sodium is not answered (at least not directly), but a lot of other interesting info is obtained

[apistomaster]

I only use salt in conjunction with treating for certain diseases or conditions like trying to promote healing of badly scraped bodies or shredded fins most often with newly arrived shipped fish. So over time, I have only had a few ocassions where my Corydoras have been subjected to salt. Usually no more than 1-1/2 tsp/gal for a week. I have never noticed Corydoras having any more difficulty with this level of salt than any other fish. I can't say I have any experience subjecting Corydoras julii(trilineatus?) to salt.

[raglanroad]

following the lead - thank you for the info I read:

Unlike other species with high Km values, the catfish Corydoras julii maintained high rates of Na+ uptake in dilute waters by having a Jmax value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L−1 NaCl, Jmax fell >50%, and Km dropped about 70%. The unusual acclimatory drop in Km may represent a mechanism to ensure high rates of Na+ uptake on return to dilute water.

Thus I would conclude that this Corydoras is able to REGULATE this intake - contrarily to other fishes

However, it would be good te try these experiments with other fishes, amongst which Corydoras, fron white water rivers, before drawing too much conclusions. The found ability might be common to Corydoras, but could olso be slecial to C julii

The sensitivity towards sodium is not answered (at least not directly), but a lot of other interesting info is obtained

I interpret the results as showing the cory studied was showing a "conservation of Na" mechanism used to better regulate RETURN to low Na, in other words "cushioning" through stocking up, in case of sudden drop in Na values...?
Dave

[raglanroad]

Unlike other species with high Km values, the catfish Corydoras julii maintained high rates of Na+ uptake in dilute waters by having a Jmax value at least 100% higher than the other species.

but this seems to say that they get lots of Na in dilute waters anyway. Maybe the response in saltier water is in order to NOT stock up, so that Na will still be flowing....? is "flow" more important than amount already "on board " ?
My earlier impression seems incorrect in any case
Dave

[MatsP]

2 mmol / liter is about 115 ppm, just to give it a better reference to those that are so inclined.

The other point is of course that they were most likely not C. julii, as their natural distribution isn't in Rio Negro. It is also unlikely that the fish they had was the usualy "C. julii" in the shops, which is actually C. trilineatus, as those come from further up the Amazon than Rio Negro. Which makes you wonder what it really was - C. kanei comes in a good place for being confused with C. julii, but not exactly identical.

--
Mats

[raglanroad]

Maybe they bought their fish in the Manaus market.

[apistomaster]

I think you will find that there is little if any difference between any of the Corydoras spp with regard to salt tolerance.

[Mike_Noren]

In my opinion you will also find that Corydoras are not more sensitive to salt than normal among catfish. Corydoras sensitivity to salt is in my opinion a myth.

I've mentioned this before, but I've kept C. paleatus for six months in a brackish water tank (roughly 2 ppt salinity) and C. schulzei, C. pygmaeus and Aspidoras pauciradiatus in very hard, borderline brackish, water. They lived and grew well for over a year.
I wouldn't recommend keeping callichthyids like that, I would expect there is a risk of long-term damage, but circumstances gave me little choice, and they seemingly didn't even notice the water was suboptimal.

[raglanroad]

I think you will find that there is little if any difference between any of the Corydoras spp with regard to salt tolerance.

I've put salt in with my corys , and obviously some is necessary. No reports here of death from salt for any cory ?

Why I raise the possibility that the fish were purchased, is because for the experiment, they may have used mostly Rio Negro ..but used corys from some other type of water..and the study then would be way messed up. potentially giving us totally false information.

[raglanroad]

In my opinion you will also find that Corydoras are not more sensitive to salt than normal among catfish. Corydoras sensitivity to salt is in my opinion a myth.

would anyone here dose them with salt as a treatment without worry, just like an angelfish could be dosed without worry ? Sea water strength salt dip ?

What I'm getting at, is that if you say "no more than other catfish"...does that mean other catfish are not salt sensitive...or does it mean they all are sensitive... corys no different


Dave

[raglanroad]

http://www.scielo.br/scielo.php?script= ... iso&tlng=e

[MatsP]

The use of salt short term is one thing, another is to "permanently" add salt to the water. A "salt dip" is not the same as using salt as a regular addition along with the water changes.

Both of the referenced documents are relatively short term, so there's no evidence here as to what happens in the long term when exposed to elevated levels of ions.

Also note that the fact that these fish don't roll over dead immediately when exposed to regular tap-water throughout the world indicates a certain tolerance to increased ion levels, as there is about 10x more minerals (including highly likely 10x the sodium concentration) in comparison to for example Rio Negro's level, and the pH is about 100-1000x higher in your average tap-water (no public service tap-water will ever be pH 4.5, it can perhaps go down to about pH 6 or so, but not much lower - it would cause too much corrosion of the water-pipe if nothing else).

--
Mats

[raglanroad]

would you say the feeling is that there is salt sensitivity , then, (compared to SA cichlids, for instance ) ...somehow..long or short term ? Or just not at all ?

[MatsP]

There is one factor that makes Catfish different from (most) other fish, and that is the absence of scales in Catfish. Other than that, they are pretty much equal in physiological terms.

The absence of scales would potentially change the ability to take up or release minerals from/to the surrounding water.

But my opinion (and that is what it can be, since I haven't experimented with this) is that catfish aren't significantly different from any other fish from the same area when it comes to salt tolerance. None of them (aside from those that live in estuaries) are particularly "tolerant" to salt.

And as I stated before, a salt-dip, or adding salt temporarily to treat some illness is completely different from the "usual" question of "should I add salt to my tank", which apparently some shops have a tradition of recommending - this may be "ok" for some species in some areas (such as many of the livebearers in areas with (very) soft water would perhaps benefit from having added salt. Soft water is of course not a problem in large portions of California or for example Texas, so those being told "buy some of this salt and add a teaspoon per gallon to your tank" in those states are definitely being misled).

Obviously, many of the traditional "common" species of tropical fish are very tolerant to MANY different things, including salt, nitrate and ammonia - some more so, others less so (guppies and other livebearers can tolerate REALLY bad water quality).

And finally, there's a big difference between "surviving", "tolerating" and "liking". If the fish had a choice, I think it would prefer water without salt - which is the basis for my answer to "no" when people ask "should I add salt with my fish".

--
Mats

[raglanroad]

I think it is odd that out all the fishkeepers, nobody can say " the corys died at one tablespoon of salt per gal, after half a day...
Or after 3 tablespoons, in one hour. Nothing to see about this. Indicating either myth or lack of curiosity, or fear very well instilled.

that's why the articles showing some physiological differences brings it back to a reasonable subject for enquiry.

Dave

[apistomaster]

Dave,
I would think that because there is no point to keeping any SA fish in chronically saline water that there has never been any reason to do so , hence a lack of experience. Salt seems to be mainly useful in short terms as in a dip or for a few days to promote healing of ragged fins.

Probably the only way to answer your question is to buy a bunch of Corydoras and experiment with differing salt concentrations until you determine the lethal dose for the species you choose to work with. I can't see where anyone else is going to do it. The basic care and needs of Corydoras is so well known that few fish keepers would intentional deviate from what is known for the pure sake of knowing how much salt and how long exposure it takes to kill Corydoras.

Let me reverse this question. How low a salinity can Plotosus endure? Or if you want a SA catfish that does tolerate full salt, brackish and fresh water, then keep some Arius seemani, a West slope of the Pacific ranges species that frequents fresh water rivers when young but lives in brakish to full marine conditions as an adult.

[raglanroad]

Larry, while that is all true, salt is a great treatment for so many issues...and if we are all avoiding salt treatments because of misunderstanding...that should be cleared up !
The OTF trade and farming industry has a big invested interest in this, not just hobbyists..catfish farming is big business and drugs are under scrutiny re: human consumption.
It seems most studies are on channel catfish though.
http://www.ars.usda.gov/research/public ... 115=200095

Dave

[apistomaster]

Salt is not used widely by the aquaculture industry for treating channel cats nor do commercial importers of Corydoras use salt. They are far more likely to rely on UV irradiation in food fish aquaculture and sick fish are destroyed as they will not pass FDA inspection. In the ornamental side of the fish business they use most of the same medications we fish keepers do. They also use UV in their filter systems.

[raglanroad]

http://www.ca.uky.edu/wkrec/SaltStressCatfish.htm

http://www.scielo.br/scielo.php?script= ... 6000300047

http://genes.pp.ksu.edu/research/public ... 115=209256

[MatsP]

Dave,

What is your point? No one is disagreeing that there are benefits, when used correctly and for a reason, of salt for short periods of time.

I don't think anyone (with some sense) is trying to say that a short period of exposure to salt will be lethal to the fish - prolonged exposure to high levels of salt is of course a different thing.

Salt on it's own, or in conjunction with other medications, can be a good treatment, no one is denying that.

--
Mats

[raglanroad]

I'm not disagreeing either...for one thing, I don't know enough to disagree....I want more information, and I do not see why I should NOT be interested ! I have corys, will be getting more, and I like salt as treatment. so I want solid information on if anyone has killed them with salt, or if anyone uses heavy salt treatments successfully. 1 tsp per gal. is quite weak solution, for most treatment.

[MatsP]

Ok. So what I want to understand is what you are looking for. Are you looking for an argument FOR keeping Corydoras (or other catfish) in saline waters permanently, or simply evidence that short term saline environments are not immediately lethal - the latter I agree with. Regarding the former, I think I made clear my standpoint:
a) don't see the point in this.
b) I don't believe it's in the fish's best interest.

--
Mats

[raglanroad]

more for salt treatments for disease. positions are not facts, and facts are what I'm looking for. anyone done sea water strength dips, for instance, without killing the fish. I could treat a whole tank with salt, where corys are the minority, and then change out the water

Dave

[apistomaster]

I agree with MatsP. Salt is not beneficial to Corydoras in the long run and I fail to see what your point is. It is something best discovered by experiments run by an interested party if one is trying to ascertain the absolute limits of what Corys can tolerate but to what ends eludes me.
I use a low dose of salt to soothe wounds rather than to treat a specific disease. Much as I gargle with salt water to sooth a sore throat.

[raglanroad]

but I do use salt, and not in small amounts, when I have disease issues. I don't like to use pharmaceuticals much. I've avoided heavy salt treatment for tanks with catfish included as a minority, without having any solid evidence to support the fears. I would rather treat the whole tank than net some fish out for treatment, or have to leave corys for other treatments in another tank.

[MatsP]

but I do use salt, and not in small amounts, when I have disease issues. I don't like to use pharmaceuticals much. I've avoided heavy salt treatment for tanks with catfish included as a minority, without having any solid evidence to support the fears. I would rather treat the whole tank than net the fish out, and leave some for other treatments in another tank.

And I think the conclusion here is that it's PROBABLY ok to treat catfish with salt, just like any other South American fish.

--
Mats

[raglanroad]

that's what it seems like. I was curious as to what experiences here were, but it seems nobody has tried recommended dosages for disease treatment ?

[MatsP]

I personally haven't, no.

--
Mats

[raglanroad]

I've used heat in the low 90's against advice, on inspectors and corys,and no fish died, but I''ve not done heavy salt on corys out of fear..I don't like not doing something out of fear, but I also do not like to experimentally kill my fish either. so it's better to find out if anyone has experience.