How to Keep Your Aquarium Fish Healthy: Essential Care Tips

The Foundation: Water Quality

The single most important factor in keeping fish healthy is water quality. Fish live in their water the way we live in air — if the water is polluted, they suffer. Regular testing and maintenance is the key to a thriving aquarium.

Test Your Water Regularly

Invest in a reliable water test kit and check these parameters at least fortnightly:

  • Ammonia — Should always be 0 ppm. Any detectable ammonia indicates a problem.
  • Nitrite — Should always be 0 ppm. Like ammonia, nitrite is toxic to fish.
  • Nitrate — Keep below 40 ppm. Regular water changes control nitrate levels.
  • pH — Most freshwater fish prefer 6.5–7.5. Consistency matters more than the exact number.

At Amazonia Aquarium, we offer free water testing. Bring in a sample and we will test it for you on the spot.

Perform Regular Water Changes

Replace 20–30% of your tank water every week with dechlorinated water at the same temperature. This dilutes waste products and replenishes minerals. Use a gravel vacuum during water changes to remove debris from the substrate.

Feed the Right Amount

Overfeeding is one of the most common mistakes in fishkeeping. Uneaten food breaks down and pollutes the water. Feed your fish only what they can consume in about two minutes, once or twice daily. Offer a varied diet — quality flakes or pellets as a staple, supplemented with frozen or live foods as treats.

Avoid Overstocking

Too many fish in a tank creates excess waste that overwhelms the biological filter. A general guideline is roughly one centimetre of fish per litre of water, but this varies by species. Research the adult size and territorial needs of any fish before purchasing.

Quarantine New Fish

Whenever possible, quarantine new fish in a separate tank for two weeks before adding them to your main aquarium. This helps prevent the introduction of diseases or parasites. If quarantine is not possible, at minimum observe new fish carefully for the first week.

Recognise Signs of Illness

Healthy fish are active, eat readily, and display vibrant colours. Watch for these warning signs:

  • Clamped fins (held close to the body)
  • White spots, fuzzy patches, or discolouration
  • Rapid or laboured breathing
  • Hiding more than usual or loss of appetite
  • Rubbing against objects (flashing)

If you notice any of these symptoms, test your water first. Poor water quality is the most common cause of fish illness. If water parameters are fine, bring a photo to our store and our team can help identify the issue and recommend treatment.

We Are Here to Help

Keeping fish healthy does not have to be complicated. At Amazonia Aquarium, our knowledgeable team is passionate about helping you succeed. Whether you need advice on water chemistry, fish compatibility, or treating a sick fish, we are here seven days a week at 8 Lakeside Road, Eastwood, Sydney.