Osphronemidae

Introduction to the Osphronemidae Family

The Osphronemidae family, better known as the Gouramis, includes several genera. For aquarium information about these fish, see the page Gouramis.

What makes these fish so special is their unique respiratory system. In addition to their gills, they have a special organ called the labyrinth organ. This organ enables them to take in air from above the water surface and thus breathe.

This adaptation evolved because the Osphronemidae originally lived in stagnant, very warm, and oxygen-poor water. In such conditions, the amount of dissolved oxygen in the water is often insufficient to breathe fully through the gills. The labyrinth organ offers a life-saving solution. However, a direct consequence of this adaptation is that their gills have become less efficient. Even in oxygen-rich water, these fish must regularly come to the surface to breathe air with their labyrinth organ. If they are unable to do so, for example due to a closed water surface, they can even drown.

Parosphromenus deissneri - Splendid gourami
Parosphromenus deissneri – Splendid gourami

First Description and Scientific Name

The history of the scientific naming of the Osphronemidae family is complex and has undergone some interesting developments. The family as a whole, as we know it today, was formally established by Pieter Bleeker in 1859 under the name Osphronemidae. It is important to note that between 1995 and 2006, this family name replaced the older name Belontiidae. The name Belontiidae included the same genera, with the exception of the genus Osphronemus, which was then classified in a separate family. The subdivision into subfamilies was also different at that time.

Although the family Osphronemidae was established as such by Bleeker in 1859, additional information is available about earlier descriptions of species or genera that now belong to this family. For example, an important early description of a fish species within this group was made by Jan van der Hoeven in 1832. This shows that individual members of this family had been studied scientifically for some time before the family as a whole was formalized.

The scientific name Osphronemidae is derived from the genus name Osphronemus, to which the well-known Giant Gourami (Osphronemus goramy) belongs. The origin of this name is fascinating and sheds light on the early observations of these fish. According to Cuvier (1831), Osphronemus is a misspelling of the manuscript name Osphromenus, which was coined by the French naturalist Philibert Commerson.

The name “Osphromenus” means ‘olfactory’ or “sense of smell.” Commerson gave this name because he assumed that the unique labyrinth organ of these fish, which allows them to take in air from above the water surface, was an organ of smell. Although we now know that the labyrinth organ primarily serves for breathing in oxygen-depleted conditions, this historical interpretation provides valuable insight into early attempts to understand the unusual anatomy and physiology of these fish. It also highlights how the labyrinth organ attracted the attention of scientists early on and has become a defining characteristic of this family.

Taxonomy, Systematics, and Evolution

The scientific classification, or taxonomy, of the Osphronemidae is a perfect example of how scientific understanding is constantly evolving. What once seemed like a simple group turns out to be a complex family with a rich history dating back millions of years. The family currently comprises about 133 recognized species, divided into four subfamilies and approximately 15 genera.

A Dynamic Classification

The current classification of the Osphronemidae is the result of years of research and revision. In the past, fish that we now consider to be gouramis were sometimes placed in other families, such as the Anabantidae. The name Polyacanthidae has also been used in the past to refer to this family.

One of the most significant recent changes is the status of the Belontiidae family. It was recently downgraded to a subfamily within the Osphronemidae, now known as Belontiinae. These kinds of taxonomic shifts occur when new genetic and morphological research provides a clearer picture of the evolutionary relationships between different fish groups.

Betta rubra - Male aggression colors
Betta rubra – Male aggression colors

Current Classification: Subfamilies and Genera

Based on the most recent scientific insights, the Osphronemidae family is divided into the following subfamilies and genera. This classification helps us to structure the enormous diversity within the family, from the well-known Siamese fighting fish to the impressive Giant gouramis.

Evolutionary History: A Look into the Past

The evolutionary roots of the Osphronemidae go back a long way, with a history stretching from the Eocene to the present day. Thanks to fossil finds, we have been able to catch a glimpse of the ancestors of the gouramis we keep in our aquariums today.

The oldest known fossil gourami is Ombilinichthys, found in the Sangkarewang Formation on Sumatra, Indonesia. These fossils date from the early to middle Eocene, which means that the ancestors of these fish lived around 40 to 50 million years ago. There was also a second fossil find that was attributed to the modern Giant Gourami (Osphronemus goramy) at the time, in the 1930s, but unfortunately this specimen has been lost. These fossils not only confirm the ancient origins of the family, but also their long-standing presence in the freshwater ecosystems of Southeast Asia.

“Fertilized
Fertilized eggs fall from Betta’s tail

Description and Ecology

The ecology of the Osphronemidae is closely linked to their unique respiratory system. They are adapted to habitats that would be unsuitable for many other fish species: stagnant, warm waters with low oxygen levels. These often include shallow pools, rice fields, and slow-flowing rivers in tropical areas.

Another striking ecological and behavioral aspect of this family is their method of reproduction. The Osphronemidae have two different, but equally fascinating, methods of reproduction:

Mouthbrooder

Fish from slightly faster flowing waters take the eggs into their mouths immediately after they are laid. The males incubate the eggs there. The young develop in the mouth for a while until they can fend for themselves. After the young are spat out, they are no longer cared for.

Foam nest builder

Fish that live in completely still water often do things a little differently. Here, the males often build a foam nest. By blowing bubbles, the males create foam in which the eggs can be suspended. After a vigorous courtship ritual in which the fish often entwine themselves, the females spawn. Some eggs are slightly oily and therefore lighter than water, causing them to float to the surface. In other species, the male must gather the eggs and spit them into the nest. These eggs usually hatch after about 24 to 48 hours. The young then remain in the nest for about two to three days until they can swim freely. The male is the one who guards the foam nest. Once the young can swim freely, they are no longer cared for.

Osphronemidae Genera in the database

Below you will find the genera within the Osphronemidae family that we have added to the database:

Osphronemidae

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