In fact, this is how most of my vivs are done. However you may want to consider leaf litter over moss (at least in most of the ground space)as moss can be rather tricky, especially on bare gravel. Another route, if you must use moss, is to take some long fiber sphagnum moss and line the gravel with a 1" layer and a final covering of live moss. Most plants grow just fine in gravel, provided that there is a small ammount of water at the bottom of the tank which should be changed out frequently (or drained if you have drains). As time goes on, alot of waste matter will collect in the substrate and by flushing it through the gravel and into the water, the plants will tremendously aid in removing the nitrates and so forth. In return your plants will have a source of food and should grow great! Also be sure that the gravel is at least 3 to 4" deep in order for the proper bacterial (helpful) development to take place. I hope this helps...it's just some of my experience.
-Bill J
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Updated list as of: 9/30/03
2.2.6 D. azureus
1.2.14 D. ventrimaculatus 'yellow' (16 tads in the water)
2.3 D. tinctorius 'cobalt' (one subadult)
0.0.3 D. tinctorius 'patricia'
0.0.5 D. auratus 'green/black' (tads)
0.0.3 D. imitator 'Alex Sens line' (1 week)
0.0.2 D. reticulatus (soon)
0.0.2 D auratus 'teal'(soon)