Need some emergency help on acclimating fish

[gabriellar]

Hi I got a longnose yellow butterfly fish from a LFS and surprisingly found out they kept the butterfly fish at 1.015 salinity after I tested the water. My tank is at 1.026. I have slowly acclimated the water in the past hour for 0.003 and this fish starting to show sign of stress by shaking his head hard. What is the quickest way to get it acclimated to my tank to minimize the potential harm to this fish? I still have 0.008 increment to go.

 

[keagan]

What did you test the salinity with? Was it recently calibrated?

 

[gabriellar]

I have a refactometer that I test my water on a daily basis, the reading is the same as the water test I got back from LFS

 

[KrisReef]

Hey, READ THIS:

Post in thread 'Newly Purchased Fish dying within 24-hrs in my QT'

Jun 28, 2026

Sorry, I forgot to mention I floated the bag for 30 minutes first. The salinity was matched, at exactly the same value (by probably pure luck).

If the meter is off, wouldn’t it be off the same for both readings? So even if off, if it’s matched, it would still be matched right?

The biggest issue with acclimation is when a dealer holds fish at a lower salinity than your tank - even with careful acclimation, you should keep the rise at less than 3 SG points (1.020 to 1.023 for example). Sounds like that wasn't an issue. Fish that are shipped have high ammonia in the water, and...

• Jay Hemdal

• 

 

[gabriellar]

Hey, READ THIS:

Post in thread 'Newly Purchased Fish dying within 24-hrs in my QT'

Jun 28, 2026

Sorry, I forgot to mention I floated the bag for 30 minutes first. The salinity was matched, at exactly the same value (by probably pure luck).

If the meter is off, wouldn’t it be off the same for both readings? So even if off, if it’s matched, it would still be matched right?

The biggest issue with acclimation is when a dealer holds fish at a lower salinity than your tank - even with careful acclimation, you should keep the rise at less than 3 SG points (1.020 to 1.023 for example). Sounds like that wasn't an issue. Fish that are shipped have high ammonia in the water, and...

• Jay Hemdal

• 

Thank you Krisreef, this is helpful. Looks like the max safe salinity swing is 0.003. I don't see this doc mention how frequent the salinity can swing for this much, I assume 0.003 per hour is safe?

 

[KrisReef]

Thank you Krisreef, this is helpful. Looks like the max safe salinity swing is 0.003. I don't see this doc mention how frequent the salinity can swing for this much, I assume 0.003 per hour is safe?

@Jay Hemdal, I don't recall the timing between steps, for raising salinity?

 

[Jay Hemdal Verified Community Expert]

Hi I got a longnose yellow butterfly fish from a LFS and surprisingly found out they kept the butterfly fish at 1.015 salinity after I tested the water. My tank is at 1.026. I have slowly acclimated the water in the past hour for 0.003 and this fish starting to show sign of stress by shaking his head hard. What is the quickest way to get it acclimated to my tank to minimize the potential harm to this fish? I still have 0.008 increment to go.

That’s really too much of a rise to handle in one acclimation event - it can take 24 to 48 hours to safely bring a fish up in salinity that far.

You’re kind of stuck though - you can bucket acclimate it with an air stone and give it multiple water additions over six hours or longer.

 

[KrisReef]

I think that lowering your DT and then raising it slowly might be easier to manage instead of messing with the bucket of fish?

 

[gabriellar]

Okay I'll try both. Thanks guys!

 

[EricR]

Okay I'll try both. Thanks guys!

Timeout!
You're not thinking of lowering your main tank with livestock (corals and other inverts?) salinity down to meet in the middle, are you?
*I'm assuming you have corals/inverts just based on glancing at other posts you've made