Ask your local swimming baths engineer he will know; i seen it done once, the pool fills with clean looking tap water by the time it's full much discolouring is apparent; then he adds a chemical, i forget which, and all becomes clear. :-)
If its a garden pond then you either need to balance the number of fish to plants and ensure that plants stop too much sunlight on the water or install a filtration system. Filtration systems are reasonably small sized and cheap nowadays.