We have a fishpond like this only our has a bunch of goldfish in it. It is also right next to our deck. It's been there for close to 20 years now. No smell at all and we have tons of wildlife that visit - dragonflies, butterflies, frogs, toads, snakes, squirrels, possum, raccoons, great blue heron, kingfisher, mallard ducks, little green heron and more. Even a turtle one time, but it was a snapping turtle, so we relocated him to a creek.
The fish have babies every year and it's fun to watch them grow and turn orange or white or orange/white combo (when they hatch they are black/dark brown and teeny-tiny). Some with long flowing tails, some with short. The goldfish eat the mosquito larvae so no problems with that.
Then when they get sort of big, they just disappear - I assume into the bellies of one of the above listed wildlife
. So I have learned not to get attached to the fish and not to put expensive koi in the pond. Our kids loved feeding the fish Cheerios when they were little, now our little granddaughter is having fun with that.
The waterfall part has extra long "steps" that provide an excellent opportunity for the birds to take a bath and I cannot begin to name all the different types of birds that come and bathe, even in the dead of winter with snow/ice all around. Our waterfall runs every day of the year. We love our little pond (but it's not as nicely landscaped as yours).