Goldfish / Carassius Auratus

Difficulty: Beginner

Probably the most kept fish in the history of fish keeping! They are sold and bred in their millions world wide and are extremely cheap and easy to come by, not to mention the huge range of colours available to choose from. Their popularity however, hasn’t stopped them suffering cruelty at the hands of their keepers, people have kept them in bowls and tiny vases for years and years and they were often looked at as “disposable” and not really a long term pet or indeed any kind of pet. Today luckily people are more aware of the facts and figures as well as laws being passed to shed light on the needs of these fish which has certainly helped. The truth is even most of the aquariums that people provide or are advised to buy from pet shops are not big enough to keep Goldfish long term, thus the aquarists are forced to either upgrade their tank size or give up on keeping Goldfish completely.

Not only do Goldfish grow large, they produce a lot of waste too so having a larger tank helps keeping their environment balanced and a larger surface area will help oxygen exchange in the water. Sufficient filtration is also key and your filter must be powerful to deal with the extra waste produced by these fish and regular partial water changes are a must. They are otherwise not very demanding and adapt to a wide range of PH, water hardness and temperature levels. Goldfish kept in outdoor ponds will even survive winter conditions given the water doesn’t freeze entirely to allow oxygen to enter. Really these fish are best suited to ponds and water gardens but given proper preparation they can make excellent in door pets!

Varieties of popular Goldfish: Comet Goldfish, Common Goldfish (Gold, Orange & White and Red) and Shubunkin Goldfish.


Common Goldfish varieties:
  • Size: 20cm/7.8inches if kept in a good sized aquarium with good water quality. In ponds they can grow to a foot in length!
  • Temperature: They are adaptable to most temperatures but prefer a range of 18C’-22C’
  • PH: 6-8
  • Water Hardness: 5-19dGH
  • Aquarium size: 13Gallons (60L) minimum for 1 fish, add 40L per extra fish. Best kept in Ponds.
  • Difficulty: Beginner
  • Goldfish only grow to the size of the tank – This is a common misconception when it comes to these fish but the unfortunate truth is if the fish is kept in a small environment it will have stunted growth which eventually leads to internal problems and death. It won’t be fast either, the fish is doomed to slow and painful death. The healthy growth for this fish is to reach close to a foot in length!
  • Goldfish can be housed in bowls – No fish can and should be housed in a bowl as it’s the ultimate cruelty because a bowl lacks filtration, space and a proper biological cycle to provide a healthy environment for fish.
  • They don’t live that long anyway – This also couldn’t be further from the truth but unfortunately it came about because of the conditions they are kept in rather than the actual life span of the fish. Goldfish can easily live to around 20-25 years under ideal conditions.