The Equipment

Some pet stores will tell you that bettas are very low maintenance fish, who don't need anything but a bowl. This is wrong in so many ways. Bettas can be low maintenance, once properly established, however, they need proper equipment to live a long and healthy life, and to assure disasters are not fatal. Also note that fish keeping is an expensive hobby, even with a small set up.
Castiel lives in a five gallon tank, which is the minimum size to house a filter. His filter is an AZOO Mignon Filter 60. Inside is an Aquaclear Foam, Aquaclear Biomax and Seachem Purigen clamped to the lid to diffuse the water flow. There is also a heater with an adjustable knob, but always shoot under when starting out with this heater, it can heat the water hotter than you think it will, perhaps being a disadvantage of a smaller tank. It is also important to have a good thermometer in the tank, and check regularly. Between 72 and 82 Fahrenheit is acceptable for a betta.
Inside the tank there is also a betta leaf hammock, which neither of my bettas have been particularly interested in but I know other bettas love them. A ceramic betta log, which is the most beloved thing by both bettas I've had, but the paint will flake off with certain harsh medications. There are also small to medium gravel rocks, and decorative glass rocks. Below the gravel for the plants, is Seachem flourite.
Castiel is fed two OmegaOne pellets in the morning, and again at night. OmegaOne also has a line of frozen foods, which Killian lived on because he hated pellets, and frozen foods are very healthy for a betta. Beware that once given a long term taste, they will not want to go back to pellets. Bloodworms, brine shrimp, and mysis shrimp are a good selection. Mysis shrimp are a must in a frozen food option for fiber in their diet. To prepare frozen food, cut a piece of one of the cubes into a glass of safe water, like spring water or RO water, for added taste Seachem has garlic guard which also helps against internal parasites. Serve with an eyedropper.
Tools to keep on hand are a net, I only use to scoop out things in the tank that should not be. A gravel vacuum for cleaning day, which should be once a week. A turkey baster, which sounds funny but is for picking up uneaten food. API water testing kit, a must. A side option is Tetra test strips, for quick and easy testing of Nitrate, Nitrite, PH and Hardness, just dip and check the colors. Tetra test strips do not cover ammonia, as API test kit does. Ammonia testing is a necessity.
For maintenance I swear by Seachem. They are more expensive but they are great products. Once a week I add Seachem Stress Guard, which is self explanatory. I also put Equilibrium in new water, which replaces the minerals taken out of spring water or RO water. And with each new gallon of spring water I put two drops of Seachem Prime in to condition the water.
Entertainment, because bettas get bored and need excitement in their little lives. A ZooMed floating mirror, to bring out their primal instincts of flaring and fighting with other fish to protect their territory. It should only be used for a few minutes at a time, fighting with their reflection for long periods of time or frequently will stress them. I have also read that a clean ping pong ball can be placed in the tank for the betta to play with.
And to conclude, Medication. Jungle has a line of treatments, which make a mess of the tank, staining anything rubber a bluish green, but they can help the fish. If you are unsure of what ails your sick fish, Lifegaurd, which treats a number of illnesses. Jungle also has Ick Clear and Fungus Clear. Seachem medications are Kanaplex, for bacterial illness like fin rot. Seachem also has Paragaurd, for parasites. And a fallback for any illness, or healing is Aquarium salt, one teaspoon to a gallon. In a pinch any table salt that does not have Iodide will do fine.
And that finishes the equipment post.
Happy Bubble Nesting!