Many thanks to all for your replies. The pond is now finished and I am just letting the water settle and gain a few nutrients for a while before we make any final decision on the fish. I am still against the idea purely because we built the pond as a haven for the wildlife so "introducing" anything unnaturally, in my opinion, is a negative move, however, my husband does have a right to his opinion

and is still trying to win me over

- watch this space!