I just got a 20 gallon aqurium(h-16" w-12" l-24") with an all glass 100w 115v-60hz heater, an aqua tech 5-15 power filter, with a gravel floor. What are some good freshwater plant and fish type. I want a fish that is'nt to demanding but more than goldfish or gupies. And if i do fishless sycling...