How long does fish need to adjust low salinity to normal salinity

[takayan]

Some shops keep fish with low salinity (1.01x). However my tank salinity is around 1.028 which is much higher than at the store.
Is a couple hours long enough for fish to adjust salinity? Or need much longer time like 1 month.

 

[Jay Hemdal Verified Community Expert]

Some shops keep fish with low salinity (1.01x). However my tank salinity is around 1.028 which is much higher than at the store.
Is a couple hours long enough for fish to adjust salinity? Or need much longer time like 1 month.

Marine fish can tolerate a drop in salinity fairly well, but they cannot handle a rapid increase in salinity. I generally try to keep any rise in salinity to a gradual increase of less than .003 specific gravity units per day. So - 1.020 to 1.023 done in increments over a full 24 hours - say in two or three steps. Fish exposed to a more rapid rise in salinity may show dehydration - they suddenly get really "skinny" as fluids are pulled out of their bodies due to the sudden increase. Not all fish are affected equally, some are fine with a faster rise, but you just won't know, so slower is safer.

I once saw a case where a child at my friend's house caught up a Tilapia cichlid and tossed it from FW to full SW and the darn fish survived! Most reef fish would die from that though!

Jay Hemdal

 

[DrMMI]

@Jay Hemdal I currently have some fish in quarantine (cleaner wrasse, purple fire goby, and a pair of diamond gobies). They were shipped at 1.016. My quarantine tank was at 1.017. Any harm in using saltwater in my quarantine ato to slowly raise the salinity over the next few weeks? Fish are in a 55g tank and I'm using a little less than 0.5g/day of ato.

 

[Jay Hemdal Verified Community Expert]

@Jay Hemdal I currently have some fish in quarantine (cleaner wrasse, purple fire goby, and a pair of diamond gobies). They were shipped at 1.016. My quarantine tank was at 1.017. Any harm in using saltwater in my quarantine ato to slowly raise the salinity over the next few weeks? Fish are in a 55g tank and I'm using a little less than 0.5g/day of ato.

That would work, but it will probably be slower than you really need to go. ATOs typically don't change more than 10% a week unless you have really high evaporation. Some people use saltier makeup water, but never mix it at more than twice normal salinity in order to avoid precipitating some of the salts.

jay

 

[Paul B]

I am not sure about this Jay. I know this is the general consensus but it doesn't seem to work in my tank. I don't think my fish care or even know about salinity.

My salinity just last week was about 1.015 because my skimmer removed way to much water because I trimmed a large amount of sponge which exudes a copious amount of "stuff" which my skimmer removes, or tries to. My ATO naturally replaces fresh water.

I don't test salinity much but I could have kept bull frogs and kissing gouramies in there.

Over the course of a day I just poured dry ASW into my reverse undergravel filter manifold until the salinity came up to 1.025.

The fish are almost all smiling and dancing the macarana. The rest of them are just texting.

Normally I wouldn't think this was a scientific fact, but over many decades I have always done this and so far, Have never lost a fish, coral or bull frog.

Is this a good practice that we should do? Of course not, but I feel it is more important for the salinity to be raised rather than care about any consequences.

As a matter of fact, I think my fish look forward to the change.

As you know, I do have a large assortment of different types of fish and I realize this salinity change thing has been around since the ice age. But it seems my fish anyway, don't seem to care.

If any of my fish get dehydrated, they just open their mouth and swallow. ;Wideyed

But of course, I am not the God of fish and just an old, retired electrician with a fish tank. ;Smuggrin

 

[Jay Hemdal Verified Community Expert]

I am not sure about this Jay. I know this is the general consensus but it doesn't seem to work in my tank. I don't think my fish care or even know about salinity.

My salinity just last week was about 1.015 because my skimmer removed way to much water because I trimmed a large amount of sponge which exudes a copious amount of "stuff" which my skimmer removes, or tries to. My ATO naturally replaces fresh water.

I don't test salinity much but I could have kept bull frogs and kissing gouramies in there.

Over the course of a day I just poured dry ASW into my reverse undergravel filter manifold until the salinity came up to 1.025.

The fish are almost all smiling and dancing the macarana. The rest of them are just texting.

Normally I wouldn't think this was a scientific fact, but over many decades I have always done this and so far, Have never lost a fish, coral or bull frog.

Is this a good practice that we should do? Of course not, but I feel it is more important for the salinity to be raised rather than care about any consequences.

As a matter of fact, I think my fish look forward to the change.

As you know, I do have a large assortment of different types of fish and I realize this salinity change thing has been around since the ice age. But it seems my fish anyway, don't seem to care.

If any of my fish get dehydrated, they just open their mouth and swallow. ;Wideyed

But of course, I am not the God of fish and just an old, retired electrician with a fish tank. ;Smuggrin

That definitely is too fast of a rise for safety's sake. I've seen fish dehydrate and die outright from a slower rise than that. Were the fish at 1.015 for very long? They may not have physiologically adapted to the lower salinity yet.

We see a huge issue here with people buying fish from a LFS at a SG of say, 1.019 and then acclimating them into a tank at 1.025 over say, four hours. The fish dehydrate and get glassy eyes and often die.

Jay


Jay

 

[Paul B]

Were the fish at 1.015 for very long?

I really don't know because as I said, I don't test much. But I imagine it happened gradually over two weeks when I trimmed the sponge.
I personally have never lost a fish but my fish are very robust and not delicate at all. It takes a lot to kill or even sicken them and as you know, they are not allowed to get any of the diseases people talk about on these forums. Remember Jay, I am like the guy you grew up with who never lost fish.

Maybe it's the clams I feed or the ones I eat myself. But I am very sure Jay's recommendations are much safer.

Unfortunately, I have to add salt every few days because of this annoying photosynthetic encrusting sponge as I have to constantly trim it or they will cover my coral. I just pour it into my UG filter.

I just did it today.