Re:Pond fever

     I cannot comment on the appropriateness of your proposed species list, 
     but I will suggest the following plants because they are all native to 
     Texas and should be able to survive a Dallas winter (and summer!)  
     Duckweed, Bacopa caroliniana, Ludwigia natans, L. repens, 
     Ceratophyllum demersum, Hydrocotyle sp., Nymphaea sp., Nymphoides 
     aquatica, Didiplis diandra, Sagittaria sp., Cabomba caroliniana, 
     Vallisneria spiralis, Utricularia sp., Eleocharis sp. and yes, even
     Echinodorus cordifolius and Echinodorus tenellus var parvulus!  (From: 
     Aquatic and Wetland Plants of Southwestern United States, D. S. 
     Correll and H. B. Correll, 1975.)
     I have seen all of these species in the wilds of Texas (except 
     Echinodorus) and they do quite well; the Ludwigia produces floating 
     leaves, while Bacopa, Eleocharis, Hydrocotyle, and Echinodorus can 
     grow emersed.  You can purchase these at just about any aquarium shop 
     or collect them from the wild, provided you have permission from the 
     I suspect platys and swordtails will overwinter OK, as I knew a woman 
     in central Texas who bred them in an above-ground pond in her backyard 
     all year long. However, I can suggest a native fish--the mosquitofish, 
     Gambusia affinis, to control mosquitoes.  They are also livebearers, 
     but not as colorful as platys. You can collect these from just about 
     any water body in the state.