Hi there, i have a 250litre tank set up for natives. it doesnt have a chiller but i live in the bush under the shade of trees so tank temp sits around 16 degrees even in summer. all my water is gravity fed from a bush stream in the valley behind my house and has no treatment whatsoever so perfect for natives. i have kept most species of natives but never giant kokopu. If you are still looking for a good home for your 2 i would be happy to take them off your hands. cheers