In Darwin, garden ponds can be used as decorative stand alone ponds, or as part of an ornamental water feature. Ponds are also suited for growing a wide range of tropical water or aquatic plants. Many of the tropical water lilies will thrive in Darwin, a reason enough to have a garden pond.
In Darwin it is more important to monitor the quality and temperature of ponds to maintain water quality that suited to both plants and fish. To keep temperature low, you may need to provide shade, and it is also important to have a pond that is deep enough not to warm up to quickly.
Shallow ponds are not well suited to tropical climates. Use strategically placed trees to provide protection from the sun, especially the afternoon sun.
Overflows are also important, especially in the rainy season.Ponds located near living areas need to have overflows that drain well away, preferably into a storm water drain.
As for fish, you have a few alternatives, the ornamental Koi are popular, however you might like to use your pond as a food supply, Barramundi and Yabbies being the two most popular to use for this purpose.
All ponds need flowing water and filtering, this keeps the water healthy as well as the plants and fish. Filters are designed to oxygenate water as well as filter, so get one installed in you pond when you build it.
Water plants can also be ornamental or edible. So consider your pond as an ornamental feature, a productive water garden or a little of both.