Trichopodus leerii

This species is a fascinating member of the anabantoid group, renowned for its ability to breathe atmospheric air via a specialized labyrinth organ. This adaptation allows it to survive in the slow-moving, often oxygen-depleted waters of its native Asian habitats, such as swamps, marshes, and vegetated streams. In an aquarium, this translates to a preference for low water flow, which mimics its natural environment and prevents it from being stressed. A well-planted tank with plenty of broad-leaved plants and floating vegetation is ideal, as it provides cover, diffuses light, and offers potential nesting sites.

As omnivores, they require a balanced and varied diet. A high-quality flake or pellet should form the staple, supplemented regularly with various frozen, freeze-dried, and live foods to ensure optimal health and vitality. Their activity level is moderate, characterized by slow, graceful movements as they navigate the upper and middle water column. They are considered medium waste producers, so a reliable filtration system is necessary to maintain water quality without creating excessive current. Socially, their behavior is complex and often depends on gender. While generally peaceful and suitable for community tanks with other calm fish, males can become territorial toward each other and other similar-looking species. It is advisable to keep a single male or a small group with more females than males to mitigate aggression. Their long, delicate fins can also make them targets for fin-nipping fish, so tank mates should be chosen carefully. With proper care, these fish can live for several years, becoming a long-term centerpiece.

Trichopodus leerii is a freshwater perciform fish belonging to the family Osphronemidae, which includes all gouramis. Its classification within the order Anabantiformes highlights its most notable physiological trait: the presence of a suprabranchial labyrinth organ. This complex structure of folded, bone-like plates allows the fish to engage in aerial respiration, supplementing gill-based oxygen uptake. This is an evolutionary adaptation to the hypoxic conditions of its natural habitats in Southeast Asia. Morphologically, the species exhibits a classic compressiform body shape, being highly compressed laterally. This body plan facilitates maneuverability within densely vegetated aquatic environments.

Ecologically, T. leerii functions as an omnivore, feeding on small crustaceans, insect larvae, zooplankton, and some plant matter. In an aquarium setting, its metabolism is moderate, and it is categorized as a medium waste producer, with a bioload factor that requires consideration in closed-system management. The species' IUCN Red List status is Near Threatened (NT), indicating that it is close to qualifying for, or is likely to qualify for, a threatened category in the near future due to habitat loss and degradation in its native range. Social behavior is sexually dimorphic; males are notably more territorial, especially during reproductive periods. This behavior is a key consideration for both conservation efforts and captive husbandry. Its environmental tolerance for salinity is very low, restricting it strictly to freshwater systems.

Breeding this species is considered moderately difficult but is achievable for a dedicated hobbyist. To begin, a separate breeding tank with calm, warm water and a lowered water level is recommended. The environment should include fine-leaved and floating plants, which the male will use as an anchor for his nest. The ideal ratio for a successful spawning attempt is one male to two or three females, which helps disperse any potential male aggression during courtship.

Sexing the fish is relatively straightforward in mature specimens. Males are typically more slender and develop longer, more pointed extensions on their dorsal and anal fins. Females tend to be plumper and rounder, particularly when laden with eggs, and have shorter, more rounded fins. Before spawning, condition the pair or group with a rich diet of live and frozen foods for several weeks to encourage readiness.

As a bubble nester, the male will construct an intricate nest of air bubbles, saliva, and plant debris at the water's surface. Once the nest is complete, he will court a female, leading her beneath it. They will engage in a 'spawning embrace,' where the male wraps his body around the female, who releases her eggs as he fertilizes them. The eggs, being lighter than water, float up into the bubble nest. The male will then diligently guard the nest and eggs. It is crucial to remove the female after spawning, as the male's protective instincts will cause him to become highly aggressive towards her. The eggs typically hatch within a day or two, and the fry will become free-swimming a few days later after absorbing their yolk sacs. At this point, the male should also be removed to prevent him from consuming the fry. The tiny fry must be fed with infusoria or commercially available liquid fry food until they are large enough to accept newly hatched brine shrimp and microworms.