Minimum 5g.
heater + thermometer
filter
gravel
plants (real or fake is your choice)
(please cycle tank for 1 week for the best chance - if possible cycle it http://www.firsttankguide.net/cycle.php)
ammonia, nitrite, nitrate, and ph testers (drop are superior to paper strip and more accurate)
I prefer a 10g and then you can add about 6-8 small fish for company (small tetras like neons, glowlights, etc, danios, or white mountain cloud minnows).
Bigger tank is more stable, and less problems. My 55g requires almost as much attention as my 10g.
Best of luck!