Molly fish hiding, tucked fins

[Mackie]

My female molly who I've had for about a year now has been acting strange. It started with her top fin was clamped and she was just hanging at the top which is not like her. I moved her into quarentine with some aquarium salt and her fin perked back up immediately, I also noticed string like poop so I fasted her for 3 days thinking maybe she was constipated. On the 4th day she was pooping, eating and swimming like normal. I added her back into her tank and she went back to hiding on the bottom with her top fin down. All parameters in the tank are stable. Amm 0, trite 0, trate 5, pH 7.4, temp 79. I live in Florida so the water is always hard. She lives in the tank with 2 of her female babys. The babys are acting normal with no issues. Wondering what the next step should be? I do weekly water changing and gravel vacs, this week I did 2- one after I took her out and 1 right before I put her back in just incase. This afternoon I added some stresscoat in the tank and shut the lights out just to make her a little more comfortable. 

Any insight would be helpful

[quikv6]

Being she responded positively to the salt (as most mollies would), I'd add some in the tank and observe.

[Mackie]

@quikv6 how much would you recommend adding? I'm unsure of the dosage being as though she has 2 small babys in the tank with her and don't want to hurt them in the process. Also I have all live plants 

Edited March 20, 2022 by Mackie

[quikv6]

Salt won't hurt them. I'd start w 1 TBSP/5 gallons. You can work up to 1 per/gallon if you really needed to, but that is pretty strong.