Funnily enough, fish can grow far bigger depending on the size of the tank they call home. Want your goldfish to live a long and healthy life, beyond 20 years and possibly grow over 30cm? Here’s how.

A goldfish in an aquarium

What size aquarium does my goldfish need?

If an adult goldfish, generally 2 years old depending on the type of goldfish, is less than 10cm long then it’s likely it hasn’t been given enough space. That means its growth has been stunted and that’s bad for its long-term health. As a rough guide, one goldfish needs at least a 50L aquarium. For each additional fish, an extra 35L capacity is recommended. That may sound like a lot of water for a few little goldfish, but healthy pets are big eaters, which means they grow quickly and produce a lot of waste. Wider tanks with more surface area are better because they allow for greater oxygen absorption.

How can I maintain my goldfish’s water quality?

Filtration and aeration are particularly important in goldfish aquariums because the breed produces so much waste, which can lead to a potentially deadly build-up of ammonia and nitrate. To help extend the life of your goldfish, invest in a good quality filter and air pump and regularly monitor the health of your aquarium with a good all-round tester kit. Any imbalances can be fixed with a simple treatment.

Also make sure to test your water’s pH, ammonia and nitrates weekly initially and then fortnightly, or bring a sample into your local Petbarn and we will test it for you for free.

How often do I change my goldfish’s water?

Good fish care requires changing 25 percent of the aquarium water every week. While you’re siphoning the water off, use a gravel vacuum to remove any leftover food or fish faeces. Later, when you replenish the water supply, be sure to add some water conditioner and check the temperature sits around 20-24 degrees. You want water changes to be as stress free for your fish as possible, so leave them in the aquarium but don’t make any rapid or sudden movements.

What you should feed your goldfish

Your fish will live longer if they get the right amount of digestible protein, vegetable matter and carbohydrates, so feed flakes or pellets specifically for goldfish. Overfed fish can become unwell so provide only as much food as they can eat within two minutes. Do this two to three times a day to avoid wastage, bloating and indigestion.