Help! Premature Fry

So today I bought a Platy home who turned out to be pregnant. I noticed this after leaving the shop but whilst she was still in the bag so Instead of putting her in my planted community tank she went straight to quarantine since she'd already squared off.
She started birthing i'd say two hours after being in the tank and gave birth to 39 fry. It was a bit traumatic for her since her third fry was stillborn and she had trouble getting it out, it was kind of half stuck in her, tail first, for over an hour and a half. On advice, I put some salt in the water and eventually it was out. After this they came every thirty seconds to no end.
A very large percentage of these fry appear to be dead, i'm assuming she was premature because of the stress of being transported from the shop. One or two wiggled out but most just sank like rocks straight to the bottom of the tank. The problem I have is that the ones that are alive barely move at all, I thought every one of the 39 had perished until I started seeing little twitches. Every so often one will come out of nowhere and attempt a huge swim to the top and then go back to playing dead.
Is it normal for them to be this still or are they all too premature and weak to make it?
I plan on keeping them in this tank to grow them out (without mum) but am unsure of what to do next. I can't clean out the dead fry at the moment because I am worried that I might accidentally discard of a live one that is just super still.

Any advice is welcome

 

If you can remove the dead ones, you really should. They can start decaying fast causing water quality issues and for premature fry, that’s a death sentence.

I would agree that moving mom caused the premature birth and likely, they won’t make it. The ones that are alive, honestly fry don’t move a lot their first day in the world. They tend to hide in tall grass or hide behind decor, but they should be “free swimming” not lying down. Keep us updated.

 

So today I bought a Platy home who turned out to be pregnant. I noticed this after leaving the shop but whilst she was still in the bag so Instead of putting her in my planted community tank she went straight to quarantine since she'd already squared off.
She started birthing i'd say two hours after being in the tank and gave birth to 39 fry. It was a bit traumatic for her since her third fry was stillborn and she had trouble getting it out, it was kind of half stuck in her, tail first, for over an hour and a half. On advice, I put some salt in the water and eventually it was out. After this they came every thirty seconds to no end.
A very large percentage of these fry appear to be dead, i'm assuming she was premature because of the stress of being transported from the shop. One or two wiggled out but most just sank like rocks straight to the bottom of the tank. The problem I have is that the ones that are alive barely move at all, I thought every one of the 39 had perished until I started seeing little twitches. Every so often one will come out of nowhere and attempt a huge swim to the top and then go back to playing dead.
Is it normal for them to be this still or are they all too premature and weak to make it?
I plan on keeping them in this tank to grow them out (without mum) but am unsure of what to do next. I can't clean out the dead fry at the moment because I am worried that I might accidentally discard of a live one that is just super still.

Any advice is welcome

It you touch them with the net and they don’t move, flush them. They are either dead or to weak to make it. Leave the mom in, it will make the fry happy-ish

 

I would like to remove the dead ones so they don't mess my water up but I can't tell which are dead and which are alive. i'm hoping by the morning if they are a bit more active I can pick them out. It's been a good few hours now and one or two of them have surprised me and have been swimming around quite quickly. They still sink back to the bottom and look dead after a short burst though. I'd like to at least give them a go since I have that tank going and don't need it for anything else. I'm feeling they are all far too small though. Should I feed them the food the adults eat just crushed up small?

 

I would like to remove the dead ones so they don't mess my water up but I can't tell which are dead and which are alive. i'm hoping by the morning if they are a bit more active I can pick them out. It's been a good few hours now and one or two of them have surprised me and have been swimming around quite quickly. They still sink back to the bottom and look dead after a short burst though. I'd like to at least give them a go since I have that tank going and don't need it for anything else. I'm feeling they are all far too small though. Should I feed them the food the adults eat just crushed up small?

Feed the fry brine shrimp or crushed up flakes

 

It you touch them with the net and they don’t move, flush them. They are either dead or to weak to make it. Leave the mom in, it will make the fry happy-ish

If I leave her in will she not eat them all? The very first one she gave birth to she picked up in her mouth and was tossing around like food. Thankfully she didn't do it again but I imagine she would when the hormones wear off.

 

If I leave her in will she not eat them all? The very first one she gave birth to she picked up in her mouth and was tossing around like food. Thankfully she didn't do it again but I imagine she would when the hormones wear off.

Normal they kill the fry that have no chance or are being mean.

 

So, interesting development. I woke up this morning ready to go and fish out all the dead ones and I only found one! All of them, even the ones that were not fully straightened out yet are moving about, not completely active yet though, still a lot of sitting around and occasionally darting about. I know they still probably won't live but it'm extremely impressed with how they've revived. Removed the dead one and did a little water change (it's so hard not to hoover them up!)
Mum has been moved back into the community tank and is absolutely fine, I thought she would have died since the process took her so long but she's swimming around with the other fishies. I can still see the tiniest gravid spot so will probably have this all over again in a few weeks.