What is causing this...Please Help

[rdefino]

This is the second time this happened. I have a 75gal FOWLR I did a 20 gal water change on Friday morning. I mixed the salt on the RODI water for 3 days. After the water change the fish started to have rapid gill movement and then by the morning 3 died. This happened about 5mths ago. Could it be the salt? I have no idea on what to do. I still have 3 fish left, seems there rapid gill movement has slowed down. Any ideas at all?

Thanks for any help

 

[nycfatcow]

hmmm i wouldnt change that much water at the same time, i usually do maybe 10g
worth. I also have a 75 gallon. Is the temp of the water the same as the tank? What about the Sg?

 

[quarryshark]

Thats a big change. What are your water parameter? Both before and after the change.

 

[Edmonton Eskimo]

A 20 gal water change in a 75 gal isn't really that much. It's only a little over a quarter of the volume. I have done much larger water changes in times of need with no troubles. Usually when I add that much new water though I do over a period of a couple hours to allow the fish time to adapt to the new water.

 

[demodiki]

There might have been a rapid change of PH involved. I don't think you could say definitively without testing the water. A rapid change in PH, temp and SG could all cause these problems IMHO.