My platies aren't in a heated tank right now. The pet store guy said it's not necessary with them as they are quite hardy. Mind you I think my 10 gallon tank keeps much warmer than the pond would, as small as it is.. I will look into your other suggestions though. My dad is away on vacation and someone was supposed to come over and feed his fish but when I went to check up on his place all but one were dead and there was only a tiny puddle of water at the bottom (how the one survived I'll never know). And of course the lawn was a jungle and nothing else was taken care of
So I thought it would be nice to at least replace his fish for him before he got back. Thanks for the suggestions!