fishmom said:
I NEED HELP--My new Betta--I got it from the nasty place Walmart two weeks ago--has fin rot--help me save my fish!! How do I save its life? What can I do? Please hurry with a reply as I do not think we have a lot of time. Thanks for your help!!!
OK, calm down.

Unless your betta has VERY bad rot, you'll most likely be able to cure him. I'm treating my first ever rescue betta Jerry for mild fin rot at the moment and I'm having good results with this method:
1. Do a 50% water change ASAP. Some people recommend 100%, but the fish is stressed and dramatically changing the water will make it more stressed.
2. Get some good medication. You can use a fin-rot specific med, but any good quality med will work. I'm using promethyasul with Jerry.
3. Add some aquarium salt to the water, according to the manufacturers' instructions. This is cheap stuff and you can get it from most fish stores.
4. Tomorrow, do another 50% water change. Remember to use meds in the new water.
5. Keep the temperature stable. An aquarium thermostat heater is great for this.
6. Keep the water quality good: 50% water changes every three days.*
I hope this helps.
(* This really only applies to tanks 1 US gallon and over. If you have a smaller tank than that, you should do water changes more often to maintain good water quality.)