The courtship in fishes

One of the things that really grab our attention in the documentaries are the different forms of courtship in the animal kingdom: the amazing dances of the birds of paradise, the pirouettes of the dolphins… But, how is the courtship in fishes?

INTRODUCTION

With almost 33,500 species of fish living around the world, it is easy to imagine that among the ichthyofauna there are a multitude of different ways of courting the opposite sex. It is for this reason that, in this article, we are going to show some of the most amazing courtships. Let’s begin!

THE CURIOUS CASE OF THE PUFFER FISH

The Japanese puffer fish creates underwater artwork to attract the attention of a female. Their creations, which were discovered just 10 years ago, consist of a pattern of circles on the seabed, similar to crop circles. It is known that these circles are part of the courtship ritual of puffer fish.

This amazing pattern is drawn by the males with their fins, with which they move the sand. The final result is obtained after a week of intense work. The pattern, perfectly geometric, measures about 2 meters in diameter and can have different shapes: from a basic model to complex patterns composed of lines, valleys and ridges, passing through mounds in the form of a crater. Some artists even look for other elements, like shells of molluscs and sediments of different colours, to beautify their work of art.

El pez globo utiliza sus aletas para dibujar el patrón de círculos (Foto: Quo).
The puffer fish use its fins to draw the circle pattern (Picture: Quo).

The most curious of all is the fact that the construction is made so that the water currents attract the finest sediments towards the centre. In addition, the radial lines that leave the centre cause that the speed of the water is reduced a 25% in the middle.

Watch this video so that you marvel at the art they have:

Females have the last word. The selection of the male is performed according to the circles: a female will put the eggs in the centre of the circular shape that she thinks is the best. Then the male externally fertilises them and then the female foes away, leaving them in charge of the male, which protects them for 6 days.

Anyway, although it is not confirmed, everything seems to indicate that what really interests the female is the fine sediment of the centre, but if so, it is not known the reason why.

Puffer fishes are not the only ones that perform this type of courtship. Another example is the featherfin cichlid (Cyathopharynx furcifer), that lives in Tanganyika Lake (Africa). In this case, they create a mound of sand, as can be seen in the photo.

Nido del cíclido de la especie Cyathopharynx furcifer (Foto: Arkive).
Nest of the species Cyathopharynx furcifer (Picture: Arkive).

THE ROMANTICISM OF SEAHORSES

The courtship in seahorses has nothing to envy to the puffer fish.

Los caballitos de mar son unos auténticos románticos (Foto: Alex Griffioen).
Seahorses are really romantic (Picture: Alex Griffioen).

It is known that seahorses are monogamous species, which means that a male mates with a single female, being reciprocal also for the female.

The courtship in these curious fish includes caresses, hugs and changes of colour. Even an authentic dance that can last up to 8 hours, in the style of Dirty Dancing. In fact, the males and females of these fish dance every morning to strengthen their bond. Such dances are also useful to know if the other partner is ready to reproduce.

I leave another video for you to see how they dance:

As you have observed, the dance consists of a set of synchronised movements, in which the two animals swim side by side as if one were the reflection of the other.

A curious fact about seahorses is that the female lays the eggs (approximately 1,500) in a male’s bag, so that when the eggs are fertilised and the embryos develop, it is the male that gives birth the juveniles at the end of 45 days.

MARIACHI’S STYLE

Okay, maybe I have exaggerated by saying that there is a fish that wins over its partner in the mariachi style, as if using a band of musicians to get its “beloved”.

Anyway, the truth is that the drummer fish (Aplodinotus grunniens) produces grunting and rumbling sounds to seduce the female.

La corvina de agua dulce produce diferentes tipos de sonido para atraer a la hembra (Foto: Dr. Hans Schneider).
The drummer fish produces different types of sounds to grab the female’s attention (Picture: Dr. Hans Schneider).

If its “music” grab the attention of the female, the couple meets on the surface of the water, where the female releases thousands of eggs into the water.

COURTSHIP WITH ROLE SEX CHANGE

We have already spoken in an earlier article about the fact that sex change is present in some animal species. What we did not comment is that some simultaneous hermaphrodite species (male and female at the same time) change roles several times during courtship.

This is the case of the fish of the genus Hypoplectrus, typical of coral reefs of the Caribbean Sea and the Gulf of Mexico.

Los peces del género Hypoplectrus cambian de sexo durante el cortejo (Foto: Laszlo Ilyes).
Fishes included in the genus Hypoplectrus change the sex role during the courtship (Picture: Laszlo Ilyes).

In this fish, courtship ensures that the two members of the partner are going to produce eggs fairly, in what has been called “egg trading”.

In this behaviour, the couple alternates the role of the sexes up to four times throughout a single mating. As males, they fertilise their partner’s eggs. To do this, the male is curved around the body of the female. I leave another video for you to see it better:

On the other hand, as females, they produce the eggs in batches, in order to ensure that they are not all generated by the same individual and, therefore, that the egg production effort is distributed.

CONCLUSION

In this article we have shown only 4 different types of courtship in fishes. As we have said, there are 33,500 species of fish recorded in the world, so that dealing with the subject in depth would require an entire encyclopedia.

Do you know any species of fish that has a curious form of courtship? You can leave your contribution in the comments of this article.

REFERENCES

Difusió-anglès

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