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Understanding pet fish behaviour

Different types of fish have different natures. It's important to understand the needs of your particular fish to ensure they're getting what they need to live a happy and healthy life.

Types of fish you might keep in an aquarium include:

  • Livebearers: these all-rounders dwell at any depth and don't need to be kept in shoals of their own kind. Example breeds are guppy, swordtail, platy and molly.
  • Surface feeders: these dwell just below the surface. They've straight backs and upturned mouths for example, zebra danio, Siamese fighting fish and hatchet fish.
  • Mid-water feeders: these have small mouths pointing forward and include angelfish, harlequin fish, pearl gouramis, glass catfish and goldfish.
  • Bottom dwellers: these have flat bodies and downward facing mouths, such as bronze catfish, pleco and clown loach.


Give your fish an interesting environment to live in by including the following in your aquarium:

  • Substrate: this is the sand or gravel on the bottom. Make sure it's suited to your fish and wash it well before use.  
  • Plants: these provide shade and shelter. It's better to provide real plants than plastic, as they release oxygen and nutrients into the water.  
  • Shelter: branches and sturdy rocks also provide shade and shelter, which are important for your fish to feel secure.

What you provide will vary according to the specific needs of your fish. For example, kuhli loaches and many catfishes will need caves and hides to help them feel secure.

Avoid overcrowding

The number of fish you can keep in an aquarium depends not only on the water quality but also on the behavioural needs of the fish. Keeping too many fish in the tank means they'll have to compete for food and they may become stressed.

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