Koi im Koiteich

Fish Ponds and Care Guide

What you need to know to maintain your fish pond!

As a Master Aquascape Contractor, Anything Wet follows Aquascapes Ecosystem approach to building and maintaining ponds.

The Ecosystem Pond: Your 5 Part Recipe for Success (From Aquascape)

The five parts of a beautiful pond recipe are the foundations of an Ecosystem Pond. Not only are the five elements the cornerstone of an ecosystem pond, but understanding how and why they go together is also the basis for successful pondering.

(1) Rocks & Gravel:

  • Rocks and gravel lining the entire pond’s bottom is an essential element to a healthy water feature.
  • In a rock and gravel filled pond, beneficial bacteria colonise on the surface of the stones and break down any waste from fish or debris, minimising its accumulation. By adding bacteria periodically to your water feature, you will help this process along by replenishing the bacteria that live on the rock and gravel as well as the filters.

(2 & 3) Plants & Fish:

The plants and animals you put in a water garden are also vital to its overall health and function. 

  • Fish consume algae and insects that inhabit a pond, and your aquatic plants use fish waste as fertiliser to grow. Keeping the right amount of fish and feeding them appropriately will contribute to the lower maintenance of an ecosystem pond.
  • Aquatic plants help in absorbing the nutrients from the water that contribute to algae growth. A pond filled with a vast amount of aquatic vegetation will be much less likely to accumulate algae than one void of plants or fish.

Fish play important roles in balancing and maintaining the ecosystem of a pond.


(4) Filtration, Mechanical, & Biological:

  • Filtration is a necessary piece of any ecosystem pond. A mechanical filter, like a pond skimmer, is needed to capture wind-blown debris before it sinks to the bottom of the pond and possibly overloads the system.
  • Biological filtration, usually handled with an external source, allows the pond’s water to flow through, creating additional biological capacity to that already in the pond, which will break down the harmful waste. By properly handling surface debris and having the right amount of biological filtration for the pond’s needs, your ecosystem pond will function at its optimal levels.

(5) Recirculating System, Pump, & Plumbing:

Not only do you need the right sized pump, but you also need the properly sized pipe to handle an ecosystem pond’s recirculating needs. The entire body of water should be circulated a minimum of one time per hour to function properly. This can be reduced in extremely large ponds or dams.

Not only does moving the water in an ecosystem pond draw surface debris to the catchment area in the skimmer, it passes the water through the biological filtration material where the bacteria can do their job. Getting the water flow back into the pond over rocks aerates it, adding oxygen back into the water.

As we have stated, fish are an integral part of any healthy ecosystem pond.

They eat aquatic pests, and mosquito larvae which breed on the surface of even the smallest amount of still water and of course provide movement and colour within the pond. As far as pets go, they are quite low maintenance and cost very little to keep.

There is a wide variety of fish you can put in your pond. We will touch on a few, but talking with Russell about your specific circumstances will give you the best ideas.


Goldfish come in a large variety of sizes, colours and shapes. They are incredibly hardy and tend to do well in most outdoor environments. They don’t like extremes in temperature: cold or hot but tend to be quite adaptable to their environment. They are reasonably fast-growing fish and will grow to the size of the environment they are kept. Popular Goldfish breeds that are easily kept in outdoor ponds are Shubunkins and Comets. Both are easily purchased from your local aquarium in various sizes and colours. 



KOI, after goldfish, are the next most popular of pond fish. They are related to the goldfish but are stockier in shape and can grow up to 80 centimetres.


Their remarkable colours, temperament and hardiness make them an ideal fish for the pond. Koi are great pond fish but are banned in all Australian states except WA and NSW because of the potential risk of them being released into the waterway and threatening the native fish in the region.  


Koi will quickly learn to recognise the voice and footsteps of the person that regularly feeds them and will even take food from the hand. They are calming to watch and will live for up to 100 years.

Koi can be kept in almost any size pond, but as these fish can grow quite large and live for many years, we don’t suggest Koi for ponds of less than 5000Litres. There is a myriad of ways to keep Koi in a smaller pond than this, but you might need to build a bigger pond later on.


Koi secrete a hormone into the water which will stunt their growth when it reaches sufficient levels (have you heard that old wives tale about growing to the size of the pond? This is why). Hence, as part of a long term management plan, we recommend doing a partial water change a few times a year. If you have a very large pond, we have large scale alternatives or could implement a rainwater harvesting system in preparation for a partial water change.


A Koi pond requires a filter and pump that runs 24/7. The more biomass of the fish in the pond, the larger and more efficient the filter needs to be. Koi are active fish and enjoy some water flow, so it is essential to have sufficient flow in the pond. We quite often have a dedicated pump and filter, and a second pump running some circulation jets that keep the water circulating (and also improve the filtration by pushing everything into an area where it can be sucked up into the filter). As larger fish and biological filters both require large amounts of oxygen, we also recommend adding an aerator to the water to supply additional oxygen. This will drastically improve your water quality and help future proof your pond.


There are a lot of fantastic Koi foods available now. The higher quality foods have stabilised vitamin and minerals, and all the essential stuff that is quite often overlooked Omega 3, spirulina, garlic and other crucial things for overall fish health and colour enhancement. Good quality food is also digested and absorbed better and results in lower levels of nutrients in the fish waste. So- put simply, a good quality fish food is one of the best things you can do to improve your ponds water quality and the health of its inhabitants. 


Koi will spawn naturally just before summer, but often the parents will eat their own eggs. When breeding Koi, the eggs have to be collected quickly and raised in a second smaller pond or have lots of rocks and plants to hide within. The spawn produced by the fish can put massive stress on the pond and very quickly overload the filters. If your pond is unfiltered, this could cause the whole pond system to crash and kill the fish.


There is a wide range of native tropical fish that can also be successfully kept in an Ecosystem Pond. 

  • Rainbow Fish (Melanotaenia, Chilatherina and Glossolepis species): Rainbowfish are generally the most popular of our native fish to be kept in ponds. They are community fish and have a range of amazing colours. The majority of rainbowfish don’t grow longer than 100mm and the minimal amount that do, are excellent community fish. Note that it has been discovered that they have the potential to grow longer in ponds than they do in the wild. This could be due to the availability of food in the pond or that they have a higher chance to live longer.
  • The Glass Perchlets Ambassis species. These small species are closely related to the Glass Perchlets sometimes offered in shops, which come from south-east Asia. The Australian species tend to be a little larger. They are non-aggressive to typical community fish and appreciate an occasional feed of live foods such as brine shrimp, daphnia or black worms. 
  • The Desert Goby Chlamydogobius Eremius is a small bottom-dwelling fish native to Artesian springs from the North of South Australia. It is peaceful and readily accepts flake foods. If offered a deep cave this species may breed in the community pond; the male will guard the eggs. Hard and alkaline water is preferred.
  • The Fly-Specked Hardyhead, Craterocephalus Stercusmuscarum has been around the pond hobbyist for many years and is a well-accepted pond fish. It readily accepts flake foods. Very peaceful and prefers to be in a school of 4-6 fish.
  • Gudgeons, Hypseleotris species. There are several species of Gudgeons suitable for community ponds—the one most commonly available in the Empire Gudgeon, a beautifully coloured and well-behaved fish.
  • The tiny Threadfin Rainbow, Iriatherina werneri comes from Northern Australia and New Guinea. It is a beautiful little fish with long flowing fins. It should not be kept with fin nippers. The Threadfin Rainbow makes a great display with very small fish like Spotted Blue-eyes.
  • The Purple Spotted Gudgeon, several Mogurnda species are not suitable for keeping with small fish, but this fish is an exciting and colourful species for a community pond containing medium to large fish.
  • Eel Tailed Catfish, Neosilurus species. This group of small catfish are generally suitable for a community pond though they may eat an occasional small tetra size fish. They do not have a problem with larger fish. 
  • Peacock Gudgeon, Tateurndina ocellicauda a small fish (to 40mm) with colours to rival the Killifish in blues, red and yellow. These fish could breed in a cave in the community pond.
  • The Blue-eyes, Pseudomugil species, are a group of small fish which make excellent community pond specimens. They are generally peaceful and readily accept flake foods. Keep the different “tribes” from different rivers separate.

 This content was originally posted on ANGFA ORG  to read more visit their website about cold water and special species.

Safety for your Ecosystem Pond

To keep your fish safe from predators, we recommend having your pond planted with a range of water plants. Plants will provide shelter and shade for your goldfish and grow on the nutrients produced by the fish waste. The plants also attract insects with their flowers which further offer food for the fish. Plants are an integral part of a healthy pond ecosystem.


Providing fish caves and rocky outcrops will also provide shelter for your fish and give A filter is vital to keep the water clear and to remove waste.


 Fish waste can become toxic reasonably quickly without a biological filter, and it is important to size your filter (and the pump that pushes the water to the filter) correctly for your pond and the number of inhabitants.


 If the pump and filter are set up correctly, the outlet from the filter can oxygenate and circulate the water creating the perfect environment for your new fish. We still recommend adding some plants as well as they form part of the overall solution.


A fish pond should be at least 60 centimetres deep and even deeper in areas prone to extreme temperatures. The deeper the pond – the more it is insulated by the surrounding soil. A larger body of water is also slower to change temperatures, so it is more likely to survive freezing or extreme heat.


During winter, you may notice that your fish will become slow, stop eating and stay towards the bottom of the pond. This is normal in the colder months and once spring appears they will become more active again. 


The temperature of the water regulates their metabolism. Below 12 degrees are considered to be “hibernating”, and you don’t need to feed them. Them somewhere to get out of the sun and away from predators.

Shop Predator Control

AquaScape Protective Pond Netting- Large (4.2mx6m)Click HereAquaScape Protective Pond Netting- Small (2.1mx3m)Click HereAquaScape Blue Heron DisplayClick Here

Feeding Your Fish

We recommend feeding your fish daily in summer, every second day in spring and autumn and once a week in winter. This can be adjusted to suit your particular situation too.  Only feed what can be consumed in 2 minutes! Excess food is polluting the water and growing algae. Leaving excess food floating around for the fish to come back to in a few hours is not beneficial to the fish or the pond. Scoop out any excess immediately and adjust the amount fed tomorrow until they are getting just what they can eat.

Feeding your fish on holidays

If you are going away and getting someone to come and feed your fish, we are pleased someone is coming to check up on your fish.  BUT, Irrespective of the individual level of pond knowledge and interest – I can guarantee they will overfeed your fish! We get quite a few call-outs to ponds full of dead fish because they were chronically overfed. I strongly recommend getting a seven-day pillbox and only leaving out enough food for the time you are away. 

Do not leave a full bag of food and instructions on how much – it never ends well. There are automatic fish feeders available, but they are a short term solution in our opinion – they are prone to not working effectively. Fish can survive quite a long time without food – so don’t feel bad if no-one can come in for a week, they will survive.

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