HELP! Pregnant Molly appears dying soon after water change

[Sanfranman]

Just did a 20 percent water change on my 55 gallon, and my pregnant Dalmatian seems to be dying. She is down at the bottom trying to put her face in the corner. Not swimming straight at all. If she dies what will happen to the fry? Should I separate her before she dies?

 

[Peteostler43614]

If she dies so will the fry inside of her. If they are born before she dies then they might survive.....

 

[Oceangirl]

Add more dechlorinator. Did you add enough? I did that once, gasping, or it could be a PH change. Check your parameters.