How gradually should salinity be lowered?

[otrlynn]

Over how many days should salinity be lowered from 1.025 to 1.009 to begin hyposalinity to deal with ich? How many days should I maintain the hospital tank at 1.009, and how many days to bring the tank back up to 1.025. I will keep the main tank fallow for 6 weeks. I have a refractometer. Thanks

 

[mbbuna]

a week each way.

 

[SaltyDr]

If you are keeping the tank fallow, the ich should die off in that tank. You would need a minimum of 6 weeks at hypo from the LAST time you saw any visible signs of ich.

 

[otrlynn]

Thanks mbbuna. For how many weeks do I keep the tank at 1.009? One fish out of four is showing obvious signs of ich. All are going to hospital tank. I'm going to try the "high and dry" method of quickly draining down the display into a new clean Brute trash can, hopefully causing the fish to swim to the corner of the tank where the water remains the deepest (the deeper area having been created by my moving a little sand). Hopefully I can scoop them out from there. I can't bear the thought of breaking down the tank and hope this works. Anyone who has experience with this method, please chime in.

 

[mbbuna]

you need to keep them in hypo for 6 to 8 weeks. so its a week going down, 6 to 8 at hypo then another week going back up

 

[tmz]

Coming up is more stressful than going down. If you take 7 days to go down you are risking a reinfestation which can be much worse than the first. Two days should do it on the downside with a week coming up.

 

[mbbuna]

<a href=showthread.php?s=&postid=12582006#post12582006 target=_blank>Originally posted</a> by tmz
Coming up is more stressful than going down. If you take 7 days to go down you are risking a reinfestation which can be much worse than the first. Two days should do it on the downside with a week coming up.

where are you getting this?

 

[Freed]

Two days to drop the salinity and a week to bring it back up.

 

[Freed]

Common practice. Search RC.

 

[mbbuna]

<a href=showthread.php?s=&postid=12582096#post12582096 target=_blank>Originally posted</a> by Freed
Common practice. Search RC.

i just did search RC and elsewhere on the net and i saw recommendations ranging from a 6 hour drop to over a week so i would say its not common practice. besides that its not the speed of the drop that kill the ich its the ich's inability to osmoregulate that kills it, so the speed of the drop has nothing to do with it and i can't see how it would risk reinfection if done over 7 days when what kills it is the 6 weeks in hypo

 

[Myrphie]

Not trying to speak for Freed, but the way I've heard it explained is that it's more an issue of the fish being able to tolerate a fast drop more readily so people try to get the salinity low ASAP to begin the hypo treatment right away.

 

[mbbuna]

my "where are you getting this" comment was really about TMZ's comment about a slow drop risking re-infestation. i only directed my next response to Freed because they answered for TMZ. if there is some documentation on this i would love to see it. but AFAIC its BS

 

[otrlynn]

Hmm. Seems like there is some difference of opinion here. I know that I have read here and elsewhere that it is much more stressful to the fish to bring it up than down. A week does seem long to get to the point that the hyposalinity is killing the ich. A small Kole tang is already covered in ich. Not really acting sick--picking on the rocks as usual, but lots of ich spots. Would like to get "treatment" started ASAP. Also, I know that a fresh water dip does not eliminate the ich, but would it be a good "head start" on treatment or is it just more useless stress???

 

[tmz]

<a href=showthread.php?s=&postid=12582565#post12582565 target=_blank>Originally posted</a> by mbbuna
my "where are you getting this" comment was really about TMZ's comment about a slow drop risking re-infestation. i only directed my next response to Freed because they answered for TMZ. if there is some documentation on this i would love to see it. but AFAIC its BS

I can answer for myself. I know what BS means but you'll have to explain AFAIC. Poor choice of words in any event.

I've dropped the salinity rapidly on many fish without ill effect. I've also seen fish dumped into higher salinity from low sg shipping water after only brief acclimation and seen them fall to the bottom on their sides gulping ans gasping. I beileve it relates to the way the fish osmoregulates. The fish's internal salinity is about 1.008.They simply have to drink less when the salinity drops and process less to maintain a balance unless the sg is taken below their internal salinity. On the other hand,a rapid drop makes it necessary for them to hydrate and this can take some time and energy.

There is a lot of good information about Cryptocarypn irritans. A web search will yeild lot's of information about it's life cycle.As a cursory primer which should make the reinfestation risk clear the following shows the picture.
The parasites in the fish leave within a few days and settle on rock glass or any other surface. They form into cysts which multiply about 200 fold .They hatch and attack over a highly variable timeframe ranging from a few days to 72 days.. This is why fish even without treatment show a few spots, seem to recover and then come down with a vicious infestation within several days to a week or sometimes several weeks.. Since hyposalinity targets only the free swimming stage of the parasites(from cyst to fish) lifecycle, it is important to get to a low level relatively quickly.

If you read through the threads you will find many where the fish was overcome by secondary infestation while the aquarist was slowly lowereing sg.

Good Luck Hope you have success.

 

[tmz]

Correction: The last sentence of the second paragraph of the previous post should read : On the other hand, a rapid RISE( not drop)...

Sorry . I'm typing too fast.

 

[tmz]

Here is a link to a nice explaination of osmoregulation in marine fish by Charles Delbeek which may be of interst .
http://www2.hawaii.edu/~delbeek/delb11.html


The relevant part is that marine fish have an internal salinity of about 1/3 of sea water,about1.008, if you do the math. There are many other articles on osmoreguation, some of which note that animals such as marine fish which are hypersmostic( internal salinity lower than their enviromment) expend zero energy to adjust to lower levels. Hypertonic animals(those in environments where external salinities exceed their internal level , on the other hand have to work very hard to maintain a healthy level of hydration.

 

[mbbuna]

i fully understand the life cycle of ich. and i fully understand how salinity changes affect both vertebrates and invertebrates( both up and down) and osmoregulation

you comment above says nothing about why a slow drop in salinity would risk a secondary infestation. and ive found no documentation to prove it

AFAIC= As Far As I'm Concerned

 

[tmz]

Well. it's certainly not bouvine excrement(BS in your parlence), language for which at least a small apology is warranted by the way..

It doesn't take a large leap to understand that if ich enters the qt tank with the fish, free swimmers which can multiply and reinfect in larger numbers in a short period of time will do so unless something like hyposalinity or copper is there to kill them.Here is just one of many pieces on the lifecycle of Cryptocaryon irritans which notes that ich will multiply 100 fold to 300fold within 6 to 8 days.So 7 days gets you a ton of them who will not be vulnerable to hyposalinity untill they are done tearing up the fish and leave for open water.
http://www.fishvet.com/Cryptocaryon.htm





I think if you fully understand osmoregulation you would not insist on a slow downward acclimation over the course of a week. Two days or less is prudent, in my estimation since it will likely insure an effective hypertonic defense against most if not all tomites.

 

[Jerry W]

Salinity can be dropped as rapidly as 24 hours with no ill effects. I've performed hyposaliniy on various occassions and speak from experience. 48 hours is suggested as a safe time frame to lower it. Raising it back should take a week. This is well documented by several disease experts. You do not need to take a week to lower it.

 

[reefergeorge]

I would think that a heavily infested fish could die in the week getting down to 1.009.

I have dropped heartier fish (triggers, clowns) down to 1.009 in 24 hrs with no problems. Take your time bringing it up, but I have in the past rush it in 3 days with no effects.