A 4000g pond might work, but it depends on the dimensions of the pond. I'd say 36'x15'12' would be the BARE MINIMUM for those fish. Which is about 5000g.
Nice fish u got there is that a silver aro ?? lool And the landscape with the tree. Its almost like in the wild =) I wish i could build outdoor ponds to. But if i do that i might be able to use it as a hockey rink during winter... Damn cold winters up here..