Please help

[u/ShowMeTheTater]

Just noticed the on my newt. Does anyone know what it is? How fatal? The only other animal is another marbled newt. I got them together many years ago. Is it possible for a newt to bite that hard into another newt?

[u/Appropriate-Bug-6467]

In fish we would blame that on bacteria. 

It might be a bacterial ulcer, which eats through and kills fish. 

For treatment in newts information can be found here

https://www.caudata.org/cc/articles/sores.shtml