A pet fish

When choosing fish note the following which indicates the health of the fish. The fish should;

  • Be clear and bright, fins held erect
  • Be alert and swim without undue effort
  • Not be sinking or bobbing to the surface, have lumps, bumps, wounds or clamped fins.
  • Not have a trail of excreta from their vent
  • Not be 'sulking' in the corner.


Goldfish are one of the most common species kept as pets. They are colourful, peaceful, and have a long lifespan. Depending on breed, goldfish can grow to 10 - 20cm so keep this in mind in relation to the aquarium you choose.



Fish require a large aquarium that provides sufficient area for the species and number of fish being kept. Fish should have ample room to swim around. Where there are more fish in the aquarium more space is needed. A rough guide for space is at least 10 litres of water per fish of length up to 3cm with amount increasing as fish size increases. Set up the aquarium with aerator, filters, pondweed, plants, smooth pebbles (up to 7cm) and a rock/item for hiding beneath. You should attempt to replicate a natural environment.


All water environments should be stabilised before fish are added. Tap water should be conditioned by allowing it to stand for 2-7 days before adding plants and fish to allow the chlorine to evaporate. Use commercial preparations to keep the pH level between 6.5 and 8.0. Saltwater tanks require experience and expert knowledge as they are more difficult to set up and maintain. If setting up a salt water tank for the first time ensure you have an experienced person to advise you and do your research properly.


When an indoor aquarium is used the water should be kept at room temperature and should not be exposed to direct sunlight as this will increase the growth of algae. Temperature range should be between 20-25oC. Tropical aquariums will require heated controlled temperature ranges depending on the species – check with the aquarium outlet or your local veterinarian for specific requirements.


Filtration is essential for providing the correct environment for the health of the fish. Mechanical filtration systems are the easiest to use.



No artificial lighting is generally required unless there are plants or the tank is set up for tropical fish. If lights are to be used they must be set to a timer. Lights should not be frequently switched on and off as this can upset the fish. Plants require light for up to 12 hours so set timers to provide this.



Where the fish may be at risk from young children or other pets (ie cats) reaching into the aquarium, or where the water is closer than 10cm to the top of the aquarium (so fish could jump out), a glass or mesh covering over the aquarium should be provided. A solid cover will assist with ensuring dust and toxins do not enter the aquarium, however do not put a solid cover over the tank unless a filter is in place and working.

DO NOT spray chemicals or cleaning products near the aquarium. These may kill your fish.

Note: always remember water safety around young children and ensure the tank is located so it is not a drowning hazard.



The aquarium should include an area for refuge from lights, action and other fish. This can be created with plants and rocky overhangs.



It is recommended that conditioned water (i.e. left to stand for 2-7 days to allow chlorine to evaporate) of the same temperature be used to replace approx 25% of the water each week. Cleaning of the aquarium should occur every term. To clean the aquarium remove the fish and place them in a covered container with 25% of their tank water and 75% fresh. Clean the sides of the glass, gravel and furniture items with fresh water. Do not use chemicals. Rinse the tank carefully and fill again with conditioned water. Refill the tank and allow it to stand for half a day before returning the fish.



Manufactured fish foods – flakes and granules, can be fed to tropical or temperate fish. Only feed food quantities that can be eaten within a few minutes otherwise overfeeding and soiling of the water can occur.

Be careful not to over-feed fish. Ask your veterinarian how much food your fish needs and how regularly it should be fed.
Supplementary feeding: Some fish may need frozen food mixtures, shrimp and larvae. Do not feed these unless directions are received from a reputable source (vet, aquarium outlet).


Health problems

Water quality is vital for ensuring healthy fish, ensure you keep aquarium clean and water fresh.   Loss of appetite, listing, skin lesions, floating upside down, poor swimming balance, spots, ulcers or growths and failure to thrive can all be indicators of illness in fish. If new fish seem unhealthy keep them separate until you can be assured they are fit and healthy. Adding them straight to the aquarium may infect other fish.


Any health issues that develop require advice from your local vet -  find your local vet here.



Fish should not be handled or kept out of the water. This damages their skin and exposes them to increased risk of bacterial or fungal infections. An aquarium net should be used for capturing or moving fish. Fish should be transported in watertight clear plastic bags, half water and half air. Transport quickly and do not leave unattended or allow the fish to heat.


Please take note and remember

Fish can make good pets but purchasing a fish should be a long term decision as they can live up to 20 years and require regular maintenance to ensure they and their environment is kept healthy.


If you no longer want to keep your fish make sure you find an alternative home. DO NOT release live goldfish (or other non-native fish) into dams, rivers or other waterways (or down the toilet) as they can carry diseases that can affect our native species and may establish populations in waterways that compete with our native populations.


If you are unsure about how to care for your fish speak with your veterinary practitioner or a person experienced in the care of fish.


Bureau of Animal Welfare