I think with your situation, a weeping moss or christmas moss would be a good plant! they dont require co2 and do not need a ton of light in order to grow.
Of course, they wont grow quickly if you dont offer them light, nutrients, and trace amounts of co2.
Otherwise, I think pennywort is a good trailing plant, but im not sure if it will hang down, so to speak.
Of course, they wont grow quickly if you dont offer them light, nutrients, and trace amounts of co2.
Otherwise, I think pennywort is a good trailing plant, but im not sure if it will hang down, so to speak.