Chinese Hi Fin Banded Sharks are a better pond fish than a tank fish. The reason why is because they are cold resistant, so they can survive the cold winters in your pond. They're PERFECTLY compatible with Koi, Goldfish, and Plecos if you have them in your pond. They're somewhat MADE to eat algae in ponds because they have a 'sucker mouth'. Keep them in groups of at least 3 though, because oddly enough, they like to school together in my experiences with them.
They are bloody expensive though, I have to say. $40.00 EACH at the place I bought my two from. So they're an expensive invesment, but they're a great pond algae eating fish as they get larger.
You need to know that these are a heafty fish! They get 1 foot 6 inches long and CAN continue to grow after reaching that length if the food is abundant. Keep them in a pond/tank of at LEAST 125 gallons.