Betta splendens

Renowned for their vibrant colors and flowing fins, Siamese fighting fish, or Bettas, are captivating aquatic pets that require specific care for a healthy life. Contrary to popular belief, these fish cannot thrive in small bowls or vases. For an adult Betta to be healthy, a tank of at least twenty liters is essential, complete with a heater to maintain a stable, warm temperature that mimics their tropical Southeast Asian home. A gentle filter is also necessary to keep the water clean without creating a strong current, which can exhaust these slow-swimming fish, especially those with long fins.

As carnivores, their diet should consist of protein-rich foods like specialized Betta pellets, supplemented with treats like frozen or live foods. They should be fed a small amount daily. The “fighting fish” name is well-earned; males are extremely territorial and must be housed alone. They will attack other male Bettas and can be triggered by their own reflection, so avoid placing mirrors near their tank. Females can sometimes be kept in groups, but this requires a much larger, carefully arranged aquarium.

Bettas have a unique ability to breathe air from the surface, so you'll often see them swim to the top. This also means you must leave a gap of air between the water surface and the tank lid. A secure lid is non-negotiable, as these fish are known to be surprisingly adept jumpers.

The Siamese fighting fish, Betta splendens, originates from the slow-moving, warm, and shallow freshwater bodies of Southeast Asia, such as rice paddies, marshes, and streams. Replicating this specific environment is the key to their long-term health in an aquarium. While they can tolerate a relatively broad pH and water hardness range, they flourish in stable conditions with very low water flow. Powerful filter outputs cause significant stress, particularly for the long-finned varieties, which struggle to swim against a current. Therefore, using sponge filters or baffling the output of a hang-on-back filter is highly recommended. The tank should be well-planted with live or silk plants to provide security and resting places. Floating plants are particularly beneficial as they dim the lighting and provide an anchor point for bubble nests, a natural behavior for males even without a female present.

Their dietary needs reflect their carnivorous, insectivorous nature. In the wild, their diet consists mainly of insects and their larvae. In captivity, a diet based solely on generic flakes is insufficient and can lead to malnourishment. A high-quality pellet formulated for Bettas should be the staple, but variety is crucial for optimal health and vibrant coloration. Supplementing with frozen, freeze-dried, or live foods such as brine shrimp, daphnia, and bloodworms a few times a week provides essential nutrients and enrichment. Their medium metabolism means they are prone to bloating and constipation if overfed; a single daily feeding is sufficient.

The social dynamics of Betta splendens are complex and gender-dependent. Males are solitary and exhibit extreme intraspecific aggression. They should never be housed together. Their territoriality can also extend to other brightly colored, long-finned fish, which they may mistake for a rival. Female Bettas lack the long-flowing fins and are generally less aggressive. While some aquarists successfully keep female-only groups known as 'sororities,' this is an advanced undertaking. It requires a very large, heavily planted tank to break lines of sight and allow individuals to establish a pecking order, and success is not guaranteed as it depends heavily on the individual personalities of the fish involved.

Betta splendens is a species within the family Osphronemidae, a group of freshwater fish commonly known as gouramis. As a member of the order Anabantiformes, its most notable physiological feature is the labyrinth organ. This suprabranchial accessory respiratory structure allows the fish to utilize atmospheric oxygen, an evolutionary adaptation to the often hypoxic (low-oxygen) water conditions of its native habitat. This ability supplements, but does not replace, gill-based respiration, and it dictates the behavior of rising to the surface to breathe.

Ethologically, B. splendens is a widely studied model organism for intraspecific aggression. The territoriality in males is primarily driven by reproductive strategy, involving the defense of a territory for nesting and attracting mates. Agonistic behavior is highly ritualized, beginning with impressive visual displays where the fins and opercula (gill covers) are flared. These displays serve as an honest signal of the individual's fitness, often resolving conflicts without physical contact. The triggers for this display are specific sign stimuli, including the vibrant coloration and elongated fins characteristic of rival males, which explains their reactivity to conspecifics and similarly adorned heterospecifics.

The fusiform body shape is typical for fishes, providing a hydrodynamic profile. However, in domesticated B. splendens, centuries of selective breeding for ornamental traits have resulted in dramatic caudal, dorsal, and anal fin elongation. While visually striking, this hypertrophy significantly impairs locomotion, reducing swimming efficiency and speed, categorizing them as slow swimmers and increasing their susceptibility to fin damage and infections.

Reproduction involves complex courtship behavior, culminating in the male building a bubblenest at the water's surface. During spawning, the male performs a 'nuptial embrace,' wrapping his body around the female to assist in egg expulsion, which he then fertilizes and collects in his mouth to place into the nest. The male provides sole parental care, guarding the nest and fry. It is critical to note that the IUCN has classified wild populations of Betta splendens as Vulnerable (VU) due to habitat degradation and pollution in their native range, a stark contrast to the global ubiquity of the domesticated form.