N.v.v. internal parasits

hello.
I think my n.v.v. male has internal parasites ...
From several months to here he eats and eats and still always really thin ...
What can I do?
I have not the slightest idea if they are worms or nematodes ...
Need some help,
Thanks, Pedro

Intestinal worms are usually nematodes. I wouldn't expect them to be the major culprit, but they could. The more likely culprit IMO is a coccidian or flagelite.

What I suggest: Move the sick animal into an isolation cage. No substrate and minimal other additions (I don't know what n.v.v stands for. If it's a terrestrial, then moist paper towels is okay for substrate). You need to see the stool and collect it as freshly as possible. Especially in an aquatic environment, many of the parasite life stages will exit the stool asap to go off and find it's next host whether that is a snail, fish, or the very same newt again. This will be species (as in the parasite) specific.
Take the fresh stool sample to the veterinary clinic. Refridgerate if it's going to be a few hours. The vet may not be able to find the exact species, however they should be able to characterize it enough to decide which medication is appropriate to deworm your animal.

Other possibilities to explain the problem that you are seeing include a intestinal disease that prevents nutritional absorption, or a systemic disease which increases the metabolic rate of the animal (hyperthyroidism for example)

Good luck!

Ian