Thank you for the lighting advice and info for the territorial behavior. I will try to get back to you with the numbers. The tank is in the middle of its third month since initial set up.
EDIT: Since I'm still a little new to aquarium care (relatively speaking... I'm trying to get the best info...
Tank is 20 gallon
1 dwarf gourami
2 mystery snails
6 neon tetras
1 female guppy
1 female platy (added two days ago)
The last water change was the day before I got the platy, and water conditions matched the store conditions.
The platy has seemed a little on edge since added, but not darting...