I would check how much weight your porch can stand. My one can stand 500kg, that's the pond plus 4 people.@Obsessed with fish is in Sydney I believe and said the pond was on a covered porch. That’s as much as I know. Fish selection is going to be dependent on whether or not the pond is going to be heated, or if the porch is enclosed and heated. As far as I can tell, winter temperatures in Sydney reach the low 60s. But I’m in NY so I really don’t know.