Fin Rot?

Ok, I'm really not sure if this is an emergency or not. I got three new neon swords almost a week ago. One of them is considerably smaller than the others. And when I got her I noticed it almosted looked like a fish had taken a small bite from her tail, It's whitish around the peice of missing fin. It hasn't seemed to get any better... I would say it's almost gotten bigger, I have never encountered fin rot. So I have no idea what it looks like. The fishes behaviour is fine. They seem to be healthy, I will try to attach a picture. Ok, I also had another question (deffinatly not an emergency) When fish rip thier fins do they heal? I noticed on one of the other swords it had a rip in the dorsal fin, but it doesn't appear to be there anymore. Sorry about all the questions. But I do have one more. If this is fin rot, is it transferable to other fish, and is there an cure not using medication? (I have shrimp in the tank and I'm sure meds will kill them) Thank you for any advice!! Oh, I have a 10 gallon tank, pH 7.6, nitrates 10ppm, nitrites 0 ppm, ammonia 0ppm. There are 5 swordtails 1 male and 4 females, and three shrimp. (2 snails also but I think they are dead)

Question 1 - the picture looks to be fin rot on the fish, especially since you say it has progressed further. Fin rot can be stopped and cured with a bacterial medication. How often do you perform water changes?

Question 2 - When fish's fins rip yes they will heal, however they do take time. And clean water always helps things heal faster.

Question 3 - Yes other fish can get fin rot, however it is a farily easy problem to treat.

So try looking for a anti-bacterial medication that treats fin rot. Take a look at a few of the links provided below.

Animal World - Tail and Fin rot
Diagnosis and treatment

Good Luck!!

Just want to check as finrot can be a underlaying problem.
You say one of the fish is not that big does it look skinny or deformed.