Keeping fish together

There are a number of factors to consider when keeping fish together in an aquarium:

  • Species of fish 
  • Water quality 
  • Behavioural needs of fish - lots of fish in a tank will compete for food which could cause stress


Despite all goldfish being a single species, there are a great many varieties. Slim-bodied, short-finned fish with 'single tails' are the natural shape. These fish are faster, better swimmers and generally more hardy.

Other 'fancy' varieties are not found in the wild, they've been bred by humans. They're slow moving and have shorter bodies and a 'twin-tail'.

Don't keep short and long-tailed varieties together. You'll find the long-tailed fish will often miss out on food as they are slower moving.

Tropical fish

Some tropical fish have also been bred by humans to produce new varieties, such as mollies and bettas. Choose species that are happy to live at different depths of the aquarium to maximise the available space.

It's important that you research the species to find out their exact requirements, including:

  • Their natural environment
  • The water hardness they prefer
  • Their specific needs
  • Compatibility with other fish

Read more on fish care and fish behaviours for further information.

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