Bitten tail

[Mouse Mason]

I was feeding my Axolotls yesterday, and (I think, because I didnt didn't see it) one of them nipped the other on the tail. Certainly, there was no damage before, and now there is a v-shaped nip out of the end of his tail. My axis get on fine when it's not feeding time, but often nip each other by accident during feeding when they go for the same bit of food, but so far there have been no injuries.
My questions are:
Is there any sign of an infection? If not- how do I prevent one from occuring (eg, do i put him in a separate container), and if there is, which i really hope there's not, how do I treat it?
Also, could this nipping be a sign they're hungry/under fed? I give them one frozen cube of various food (I have a mixed pack, but its mostly blood worms) a day, and they are both about 2/3 months old.
Finally, I'm sorry if I sound paranoid, ita just I'm new and this has never happened before, so if there's any questions I've forgotten to ask/advice you want to give, please tell me!
Oh and final, final thing- the pictures where taken just after feeding, which is why blood worms where everywhere, I do take out what they haven't eaten after a short time, and Skipper (the nipped axolotl) wouldnt stay still for more than two seconds which is why the photos are a bit blurry

 

[Mouse Mason]

I'm quite worried now- Skipper's tail seems to have some white on its end, I think it might be some kind of fungus, and overnight Charlie (my other axi) has developed some grey patches- please can someone tell me if something is wrong, and what to do about it!

 

[Tarabull]

The grey patches on the side of the face are normal to sometimes notice. It is their slime coat. Sometimes the slime coat will be more noticeable if the water parameters are off. On the tail, if the white doesn't look fuzzy then it could just be some of the skin and damaged tissue on it. Make sure that you are testing your water and keeping it clean. Your little one should heal quickly.