Pond Fish Health: What You Need to Know

Ponds are a fantastic addition to your backyard. Watching your fish swim happily about is relaxing and enjoyable. But do you have a pond that promotes the health of your fish? Several factors influence whether a pond is habitable by fish, so before your stock your new pond or choose a few new finned friends at your water gardening store, take a few minutes to assess your fish’s dwelling space as it relates to pond fish health.

Size Matters

It all starts with the size of your pond. You need to make sure that it is large enough to support fish and their growth. Pond fish generally need 16 litres of water for every 1cm of their length (6.25cm per 100L), and you have to be ready for them to grow larger, so be careful not to overstock, no matter how tempting this may be! Some pond experts go so far as to recommend only 4cm fish length per 100 litres of water as a maximum stocking density.

On occasion, you may encounter ponds crowded with 7 or even 8cm of fish per 100 litres of water and the fish seem to be fine. However, the density and ecological strain of this loading turn these ponds into fragile systems. The pH tends to sag, the fish tend to grow more slowly, and disease can become a common occurrence.

You won’t be able to salvage sick fish in a pond that’s overcrowded. Eventually, Mother Nature will pick off your favourite fish to achieve her ideal stocking density based on the system the fish are in, and then the remainder will recover as if by magical intervention. So reduce the number of fish if your pond is over-stocked before Mother Nature handles this crucial step for you.

Good Morning, Sunshine

Ponds that have some sunlight are also beneficial to fish due to the valuable vitamins that are produced. Sunlight also helps the plants in your pond grow, thereby reducing nitrates in the water. Unfortunately, you can’t just up and move your pond, so if you have a shaded pond simply add shade-loving plants to help balance the water. Aquatic plants play a critical role when it comes to enhancing pond fish health.


When it comes to pond depth, most fish aren’t very picky. Just be sure that the pond is deep enough (generally about 60-70cm) to give the fish a chance to get out of the way of predators.

A Balancing Act

The quality of your water is critical to pond fish health and you want to make sure your water garden is balanced. The proper mix of fish, plants, filtration, circulation, and rocks and gravel all provide an important role in your pond’s ecosystem. Work with Mother Nature, not against her, and you’ll find you spend more time enjoying your pond and less time maintaining it. Consider adding the Aquascape Automatic Dosing System to keep your pond water balanced and your fish healthy throughout the season.

For more information and expert advice on stocking your backyard pond, give us a call at Aquascape Supplies Australia.

Renovation Business