Fish Ponds

Keeping fish is one of the easiest pastimes.

The joy of watching fish swimming around in fish ponds can be quite mesmerising and relaxing at the same time. Conversely, a pond without fish may often seem lifeless.

At some point in time, most people who contemplate having a pond, invariably feel that it should include some fish. However, many mistakes are made and many fish are unnecessarily lost, because no thought was put into their needs and also how they change the whole dynamics of the ponds’ ecosystem.

What type of fish?

Gold fish are the most popular choice, especially if you are starting out with your first fish pond. They are ideal for almost any sized pond. Gold fish are small, hardy fish that are colourful and relatively inexpensive.

If you are planning to build Australian native fish ponds, you should consider selecting Australian native fish. Seek advice from reputable fish breeders, as the wrong choices, for example – gold fish or the wrong native fish, in your native pond can change the balance in the habitat that you are creating. Some fish may eat the tadpoles and so affect the balance of your native frog populations.

Can I have a pond during water restrictions?

Yes you can! Fish and other aquatic pets are exempt from water restrictions. You need to keep them alive. However, if you are planning a new pond, check with your local authorities before filling your new pond.

How big should my fish pond be?

Fish ponds can be almost any size, provided that all the fish’s needs are met – food, oxygen and healthy water. Smaller ponds in full sun heat up faster and warm water also has less oxygen. So if you wish to have a small pond, then some shade or increased pond depth can help keep the water cooler.

How many fish?

If you were to look into the water at the beach, in a lake, a river or a stream.  How many fish would you see? 

Not many.  This is the underlying problem that we have with ponds.  We are trying to create an artificial environment and then wonder why it’s sometimes hard to look after.  It’s out of balance.  It’s over stocked.

How many fish is difficult to judge, as all fish ponds are different. Unfortunately this seems like a cop-out but it is a fact. The balance between pond size, depth, sunlight, aeration, pumps and filters all affect the final result. 

Over stocking a pond with fish, can result in the build up of toxins, such as high levels of ammonia, nitrates and nitrites, as well as algal blooms.

There are a few rules of thumb that we have come across.

Then, there is the fact that an aerated pond can usually sustain twice as many fish as an un-aerated, still water pond.

  1. Some work on weight and suggest 1 kg of fish per 1000 litres of water.
  2. Others work on length and recommend about 30cm of fish per 1m² of pond area.

Our recommendation

Start off with smaller fish in a new pond, as they tend to acclimatise much easier. Then introduce more, as your experience with maintaining your own pond increases. Seek advice from reputable fish breeders.

How often should I feed my fish?

Fish are just like us humans. Too much of a good thing is not necessarily the best thing for our health or theirs. Overfeeding is wasteful. The fish cannot digest all the food properly, resulting in increased fish waste or food that is not eaten at all. Both lead to increased levels of ammonia, nitrates and nitrites, which are the perfect for algal growth.

When feeding, only provide them with what they can eat in a few minutes once or twice a day. During the cooler months, their metabolism slows, feeding should then be reduced and often there is little if any need to feed them at all.

Larger, more established fish ponds require little if any supplementary feed. At Oz Watergardens, we never feed the fish. Most of our ponds are full of the plants that we grow. The plants provide food, shelter and also create an environment that attracts other life, such as insects that they can eat.

The fish help us keep the ponds cleaner and healthier by eating some of the algae, controlling some aquatic pests that may be harmful to our plants and by eating the mosquito larvae.

Do I need plants and filtration to create healthy fish ponds?

Submerged plants, sometimes referred to as oxygenating plants, are great water clarifying plants, through the fact that they consume the same nutrients in the water as algae.

What would you rather have – green water or more plants? This balance is more difficult to achieve in smaller fish ponds, as small changes can have major influences in the pond environment.

The solution is to include a biological filtration system to help consume the nutrient load. Some even have UV lights that can kill algae.

Good plant selection helps keep your pond healthy

You should select plants to help create an environment that will benefit the fish. Plants for fish ponds need to provide shade, places to hide in, a direct source of food or a place that encourages other organisms that the fish can feed on. Some plants provide oxygen, while others help improve the water quality through natural filtration.

We recommend that all fish ponds should have some plants from each of the five Pond Zones in order to achieve a healthy balanced ecology.

Here are a few of our recommended plant combinations for fish ponds. But remember, that every pond is a reflection of your own personality. You can create the look that you are trying to achieve by selecting plants that suit your own style.

Selection 1- Fish Pond

Zone 1 – Lemna (Duckweed) is a great food source for many fish

Zone 2 – Acorus gramineus ‘Ogon’ (Golden Japanese Sweet Flag)

Zone 3 – Bacopa monniera (Water Hyssop) provides trailing foliage for fish to hide in and is great for fish spawning. Oxygenating plant.

Zone 4 – Cycnogeton procerum (syn. Triglochin) (Water ribbons) water filtering and oxygenating plant.

Zone 5 – Nymphaea hybrids (Water lilies) provide shade and a food source, as algae often grows along the leaf stems and is eaten by many fish. Vallisneria Americana (ribbon grass) grows into lawns of water filtering foliage.

Selection 2- Tropical Look Fish Pond

Zone 1 – Lemna (Duckweed) is a great food source for many fish

Zone 2 – Hydrocotyle verticillata (Shield Pennywort) for pond edges.

Zone 3 – Myriophyllum crispatum (Upright water milfoil) provides trailing foliage for fish to hide in and is great for fish spawning.

Zone 4 – Nymphoides spinulosperma (Showy Marshwort) provides shade and water filtration.

Zone 5 – Baumea articulata (Jointed Twig rush) shelter and water filtration.

Selection 3- Lush Look Fish Pond

Zone 1 – Pistia stratiotes (Water Lettuce) these drifting plants have great feeder roots that filter the pond water and fish love to play around in the roots. (Note that this plant may only be grown in SA. Tas and Vic. It is a declared weed in all other states of Australia.)

Zone 2 – Colocasia varieties (Taro) Lush tall foliage to create some shade and good feeder roots to filter the pond water.

Zone 3 – Bacopa carolinana (Lemon Bacopa) a nice lush plant for warmer pond that provides shelter and oxygenates.

Zone 4 – Pontederia cordata (Pickerel Rush) shelter and water filtering plant.

Zone 5 – Nymphaea hybrids (Water lilies) shade and a food source, as algae often grows along the leaf stems and is eaten by many fish. Vallisneria Americana (ribbon grass) grows into lawns of water filtering foliage.


  1. To choose your own selection of plants refer our Zone Map page
  2. For information on plant care, go to our Tips & Hints page.
  3. Click on the following link for information on Pond maintenance

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