Pond fish dieing? Too cold?

[Ellie]

Probably about 2 or 3 months ago we built a pond in our backyard, we waited 2 weeks with the pump on and filled with water and some plants for the water to be right. Then we added some small goldfish to the pond and a few weeks after that some platys.

Now it's winter (in Australia) and a lot of the fish are dieing. It can get to 2 C at night and then at most 25 C during the day, but it's usually around 8 C at night and 21 ish during the day. Why are my fish dieing? It's not over crowded (my pond is big enough for them), they're getting fed enough (1 big pinch morning and night), I'm not sure if something is eating them...they're still in the pond when I find them (obviously I take them out when they're dead, but in the morning when I get up), they do have bites taken out of them, so I'm thinking it's too cold and the goldfish are eating the platys (only the platys have bites on them, but the goldfish are dieing aswell, just less of them)

So is it too cold? Goldfish are eating the platys? Something else?

Thanks everyone!

Oh! I just thought of something, it might be chlorine! The water level keeps dropping so we are filling it up every day (we're fixing it) and I don't usually put in declorification (sp?) stuff in. I will start putting it in now.

[Gerlie]

actually, you need to overcrowd the pond to make the release more heat in the pond because you mentioned that its winter... or you need to transfer them to a fishbowl and place it in a warm place. Quick! before the pond is frozen!!!