Sea Fish

Ketodonts, Butterfly Fish

  • Scientific name: Ketodonts
  • Common Name: Butterfly Fish
  • Aquarium size: 1,000 liters
  • Temperament: Calm
  • Temperature: 24ºC to 26ºC
  • pH: 8.2 to 8.4
  • Diet: Algae and microorganisms
  • Length: Up to 20 centimeters


The so-called butterfly fish are marine fish that belong to the Ketodontid family, where we can find other genera that are also known as butterfly fish: Chaetodon, Chelmon, Forcipiger and Heniochus.

We are thus facing a fairly large group of fish that covers some
127 different species, which share common morphologies.

They also share a common characteristic that interests us, if we want to have them in our aquarium: they
are very difficult to acclimatize.

They are very delicate fish to eat, so there is a first phase of adaptation that is crucial.
If they are able to get used to the new feeding of the aquarium, its maintenance will be much easier.


All butterflyfish are laterally compressed and oval in shape. They are adapted to the environment to which they belong, the coral reefs.

The size that they can reach within the aquarium varies from one family to another, but we could establish a size that ranges from 10 cm long for the smallest species, up to
about 20 centimeters for the largest specimens.

In nature they can reach up to 30 centimeters, but it is very rare for them to grow so much in the aquarium.

The Chaetodon have a very sharp mouth, which
in the Chelmon family becomes a very long snout, specially designed to feed on algae and microorganisms that live among corals.

They have very striking and attractive colors, which makes them a highly desired piece in a marine aquarium: yellow, black, white, red, blue and orange.

Some have spots that resemble the
ocelli of butterflies , and this is where the nickname of Butterfly Fish comes from.

Distribution and habitat

They are widespread in tropical seas, with a large presence in the atolls of the Indian and Pacific oceans.

Their natural habitat is the coral reefs, where they find their food and also their refuge from their natural predators.

Younger specimens can frequent coastal areas, but
older ones rarely leave coral substrates.

Aquarium conditions

An aquarium suitable for keeping butterfly fish will have a minimum size of about 500 liters, although depending on the species we can go up to 1,000 liters.

It is convenient that the aquarium has corals and holes to hide in.

The water must have the following characteristics:

  • pH between 8.2 and 8.4
  • Temperature between 24ºC and 26ºC
  • Density between 1.023 and 1.026

Regular water checks and renewals must be carried out.
They are very demanding with the quality of the water .


The most conflictive point and why it is so difficult to adapt Ketodonts to aquariums, is their high specialization in their diet .

In nature
they feed almost exclusively on algae and microorganisms found in corals, which is why they are so closely linked with them.

If we can get them through the adaptation period (which is quite difficult), most Chaetodon
accept tubifex, Artemia, and freeze-dried shrimp. Some species also consume tentacles of actinias or Cerianthus.

Behavior and compatibility

They maintain a rather complicated relationship with other specimens of their species, however, they can share an aquarium with other fish, as long as they do not have liveries and colors similar to those of their species.

If so, they would see them as a rival and attack them.

They are quite solitary fish.
In a community aquarium
they should be raised alone or in pairs , it is not advisable to put several specimens from what I have said, they would face each other.

They have diurnal habits, feeding during the day and seeking shelter from corals at night.


Reproduction in the aquarium is not easy and there are not many success stories.
In nature they release the eggs into the water , becoming part of the plankton until they hatch.

As a curiosity,
the young of the Ketodonts when they are born their body is covered with sheets that protect them from predators. This stage is called tolichtis.

Photos of the Butterfly Fish

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