whats the best sort of plants to keep in a guppy and swordtail tank? so far i've tried 3 different plants and they've all been nibbled to death. one (oxygen weed) almost had a chance to attach to the bog wood but then the guppies got their killed it and the swordtails finished it off. its almost like their not eating but they are. also i've got coral sand in the tank with them so maybe the alkaline is too high. more than one bloke at the lfs said livebearers would be fine with it but now their eating the plants like its no tomorrow.