As this is my first post to Aquaria Central, I would like to say I am a advanced beginner who would like some advice on stocking my planted, cycled 4 gallon tank. A picture of the basic system is found here. Nitrate and Nitrite are both at 0, and the pH is about 7.0, leaning towards 6. The plants in my tank are a banana lily, a crypt, and several small sword plants, all of which are thriving. I understand the small nature of my setup limits my stocking options, but I am currently leaning towards either a couple of Western Mosquitofish or a single male Betta. I also would like a recommendation for a good heater for my tank, as I have not purchased one yet.