Pterophyllum leopoldi - Territorial behaviour

Communication between Pterophyllum or how Angels talk

Obviously Pterophyllum or the genus of the Scalare, Altum and Leopoldi cannot really talk to each other. What many people don’t know is that they can communicate with each other. Not only Pterophyllum communicate, but also other species communicate to a greater or lesser extent.

Communication between Pterophyllum happens in 3 ways. There is a chemical, acoustical and visual way of communication by means of smell, movement or distinct colouring of bands.

Pterophyllum leopoldi - Neutral colours
Pterophyllum leopoldi – Neutral colours

Chemical communication

Chemical communication happens by releasing different chemicals signal in the urine and bile acids. With these chemical markers, fish can indicate their reproductive status, recognition of species and warnings in case of predators. Also finding the right mates and their social hierarchy can be deducted in this way.

It is important to know that in an aquarium this can have an effect due to the water changes that we do. The greater the water change, the greater the chance that certain chemical communications will occur again.

Acoustical communication

Acoustic communication in fish species is done by moving sonic muscles that resonate at the swim bladder. Sonic muscles are one of the fastest moving muscles in vertebrate animals. The muscles ensure that the swim bladder emits one tone per contraction.

Fish use acoustic signals during mating and spawning, during agonistic behavior (threatening, fleeing, attacking behavior) and during competition during eating. A well-known fish species that communicates with acoustic signals is, for example, the Croaking gourami and a number of catfish when they begin to grunt.

If you look at the Pterophyllum, for example during mating behavior, you can see that these fish start to shake their head / body briefly and quickly. During this spectacle, among other things, acoustic communication is used. We cannot always hear acoustic communication in fish.

Visual communication

Visual communication with fish can be done in various ways. This can consist of using the position of their fins, changing the intensity of their colors and of course by making use of the crossbands that certain cichlids show or changing patterns on their bodies. Visual communication is what we as hobbyists will notice most in our fish species.

Pterophyllum make use of changing the intensity of their bars. During territorial behavior, Pterophyllum not only uses the position of their fins, but also the intensity of certain colors, such as the intensity in the vertical bars.

Pterophyllum leopoldi - Territorial behaviour
Pterophyllum leopoldi – Territorial behaviour

Visual communitcation with Pterophyllum leopoldi

With the Pterophyllum leopoldi one can see that during territorial behavior the crossbars darken, but also that the specimens show all 8 bars. If we look again at impressing behavior with a starting couple of Pterophyllum leopoldi, then you see that the 6th and 7th bar are black, while the other bars have faded. You can also see the green metallic spot on the gill lids becomes darker in color. During mating behavior you will see that Pterophyllum leopoldi will darken the 4th, 6th and 7th bar. The 5th bar will only show a black spot / dot. The green metallic stain on the lids is also more intense in color.

Pterophyllum leopoldi - One fish of a couple during mating
Pterophyllum leopoldi – One fish of a couple during mating

Pterophyllum altum visual communication

With the Pterophyllum altum you can see that they have four dark bars (foreground bars – 1st, 3rd, 5th and 7th bars) and three lighter bars (background bars – 2nd, 4th and 6th bars). Healthy specimens in the aquarium will generally show the four dark bars, which will be light brown to dark brown in color. The three lighter bars will not always be visible. The altum can also show some red pigment and this may vary in intensity per variant.

For specimens that are nervous, shy or specimens that do less well, the four foreground bars will be lighter in color and the background bars will hardly be present. The red pigment will also be almost less present in this situation.

During illness or stress situations the four foreground bars will be very dark in color as well as the three background bars. The body color will mainly be dark and gray, with virtually all red pigment color disappearing.

Pterophyllum leopoldi - Strepen bijna onzichtbaar
Pterophyllum leopoldi – Striping pattern nearly invisible

If one looks at the altum during mating behavior, the four foreground bars will become intensely blacker and the background bars will get a more light brown / red color. All this will be different per species within the genus Pterophyllum and the place of origin of the Pterophyllum.


In addition to the above-mentioned visual communication, it also has another function in the wild. It gives the species an ability to adapt to the living environment at that time by changing the intensity and number of visible bars. This can also be seen with Angels that are kept in a black water tank, or kept in a well lighted aquarium. The intensity and variation in color adjustment is also visible here.

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