Summarize this article in one sentence.
Pet stores often will not carry Betta fish medication, meaning that you will need to order it online. If you do this after your Betta fish gets sick it will likely be too late. Complete first aid kits are available online.  However, you can try to save money by ordering the necessary supplies separately. Basic medications include: Bettazing or Bettamax, Kanamycin, Tetracycline, Amplicillin, Jungle Fungus Eliminator, Maracin 1, and Maracyn 2. Most Betta fish ailments are caused by improper feeding and cleaning. These will be examined in greater detail later. However, a few things to always keep in mind include:  Clean the tank regularly. To keep it clean, do not overcrowd with too many fish, add aquarium salt to water, and disinfect the tank. To limit the spread of disease from one fish to another, immediately remove dead fish, quarantine new fish for two weeks before introducing them to a tank, and wash your hands after handling fish.  Do not overfeed fish or allow food to rot in tank. The most obvious way to tell that a Betta fish is sick is to observe whether or not it wants to eat. If it is not eating or appears unexcited at the sight of food, it is likely sick. Other signs of illness include a less vibrant color or strange discolorations. Others signs that your betta fish is sick include: rubbing against items in the tank as if to scratch itself; swollen, protruded eyes; raised scales that protrude out toward you; lethargy; and a fin that is clumped together rather than spread out.

Summary:
Keep a first aid kit. Prevent illness. Know how to recognize the first signs of illness.