Wild-caught mudpuppy not eating

So, this amazing creature (Necturus maculosus)just sort of fell into my lap about 5 weeks ago. She was wild caught in Minnesota, driven down to Georgia and lived in a tupperware container with four other N. maculosus for a week in a convention hall. I brought her back to Alabama and have her in a 55 gal. tank but it is only have full. (I read they live in shallow water?) She has three hiding places, and I put river sediment and rocks for turtles in for substrate. I have live floating plants and some bulbs in pots sunk into the sediment. I have offered here redworms, nightcrawlers, goldfish, minnows, and one of my bearded dragon's superworms out of desperation last night. She bit at the redworms and the superworm but ultimately left them uneaten. I removed the goldfish but the minnows swim all around her and she doesn't seem at all interested. The water temp. stays around 60F with a 2 degree fluctuation in either direction, depending on the humidity, ammonia is 0.5 ppm, nitrate and nitrite are negligible, not even registering at 0.5 ppm and 0.3 ppm (these are the minimums on my test kit) respectively, pH is 7, DO is 4 ppm. My phosphate test registered a whopping 4 ppm, which worries me. I do feed the minnows flake food everyday. In short, any hints, tips, or tricks on getting this salamander interested in eating again? I have ordered ghost shrimp and crayfish through a local pet store (I tried 5 before I found one that even offered to try to get some in stock) but it will be next week before they come in. I have read opinions for and against feeding frozen. Any thoughts on what I should try, if any frozen foods?
I have tried to post a couple of video clips of her so that people may get a better look at her but they won't load. I can send them to you if you are interested. I think I attached a picture of her, at least.

Mudpuppies are commonly found in deep water. I would fill the tank up. When I kept a mudpuppy for several years, it was in a 55 gallon.

Does this mudpuppy have any gill filaments left? I don't see the bushy red gills of a healthy animal or it may just be a bad photo.

They love earthworms and minnows. Be careful of minnows though because they will nip at the gills of the mudpuppy, and minnows can carry pathogens/parasites.

I would suggest placing as many hiding spots as possible. Something like PVC pipe or a tube that the mudpuppy can crawl in will make it feel comfortable.

Lastly, leave the mudpuppy alone. Stop bothering him/her and give him/her time to adjust. Your not going to help the mudpuppy eat if you keep stressing it out. Perhaps you can take the minnows out, stay away for a few days, and come back and place minnows or nightcrawlers in at night.

Hope this helps,

Blake

The first thing I notice is your nitrate. It should be at least 5.0 ppm. I would try adding more plants, hides, and maybe more water. But, she very well could just be stressed from the transition. It may take a while for her to settle in. Besides that, I am out of ideas. I hope this helps you out a bit. -Seth

Her filaments fell out. It looked like beard stubble in the bottom of the tupperware she was in.

Oh dear, it sounds like she's probably trying to recover from ammonia poisoning, As others have already said, you need to disturb her as little as possible and make sure water quality stays perfect.
I'm not sure what Seth means by nitrate needing to be 5ppm?? I'm pretty sure in her natural habitat it would be pretty much zero.
Hope this helps.

Nitrate - can be anything from 0 to around 40ppm. Your reading is fine.

Ammonia - if you are using test strips, these are notoriously unreliable. If there really is ammonia at 0.5, this is a significant concern.

River rocks - OK, except that they tend to trap debris underneath. Be careful that there is no uneaten food falling down there.

What kind of filtration and/or aeration do you have? Well-aerated water is a must. I'm not very familiar with test kit readings for DO, but here is a page with some info:
Oxygen in the aquarium
The units of mg/l are (sort-of) equal to ppm. I believe your DO is too low, especially for an animal with compromised gills.

Phosphate - could be coming from your tap water. Have you tested your tap water?

Redworms - have a funky smell/taste. Try Canadian nightcrawlers instead.

Good luck!

Sorry, I think my post was badly worded, regarding the nitrate I didn't mean that your reading was a problem, just that there nothing wrong with it going below 5ppm.
I hope she makes a speedy recovery!