Thats nothing.. clean it and change to paper.
The fussy eaters jn this house do not get adults rats. You should see a bite from a medium adult. That will really make you panic. You have a nick there and nothing more. I suggest you feed multiple smalls to a Ball that only takes live... Balls are nothing like large constrictors and its easy for them to loose a battle with a adult rat quickly.
I myself have not known a Ball that will not take a fresh killed when done correctly. Id look into it. If you want to try it, just skip a feeding so their extra hungry. Present the fresh kill as soon as its dead.. good luck.
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