Newt larva curled tails

[Lilibugz]

Hello I’m raising newt larva for the first time in a while and they’re not doing so great. I’ve lost a few over the week and the survivors all have curved tails. I noticed during a water change that some of them are swimming in a jerking motions, sort of circular or in an S shape. I’m not sure why they’re doing this and really don’t wanna lose anymore. The water perameters are fine, I’ve been using aged dechlorinated water. I was doing around 20% water changes daily and I’ve switched to 100% since I started having issues. I’m feeding live BBS separated from the eggs with a net and rinsed thoroughly. There’s Java moss and oak leaves in their set up. Any help would be greatly appreciated.
I linked a video of one swimming, a photo of one with the worst curve and one with the least curve.

 

[Lilibugz]

Apon further research I think they may have a bacterial infection. I added some melafix to each container. They’re so young I’m not sure this will help but I’m hoping for the best.