Copella arnoldi

The Splash Tetra is a small, active freshwater fish from South America, famous for its unique breeding behavior where it lays eggs out of the water. This peaceful species thrives in small groups and occupies the upper levels of the aquarium, making it a fascinating fish to observe. Due to its shoaling nature, it's best to keep them in groups of six or more to ensure they feel secure and display their natural, lively behaviors. While they are generally peaceful, they can be easily intimidated by very large or overly boisterous tank mates, so choosing companions of a similar size and temperament is important.

As omnivores, Splash Tetras are not picky eaters and will readily accept a varied diet of high-quality flakes, small pellets, and occasional treats of freeze-dried or live foods. A healthy diet contributes to their potential multi-year lifespan. One of the most important considerations for keeping this fish is its tendency to jump. A securely covered aquarium is essential to prevent them from escaping. While beautiful and engaging, they are better suited for aquarists with some experience, as they require stable water conditions and a thoughtfully arranged environment to truly flourish.

Native to the slow-moving streams and tributaries of South America, the Splash Tetra has adapted to a specific set of environmental conditions that should be replicated in the home aquarium. These waters are typically soft and acidic, often stained with tannins from decaying leaves. Therefore, they do best in an aquarium with gentle water flow, which mimics the calm waters of their natural habitat. A well-planted tank with floating vegetation provides cover and diffuses light, making these top-dwelling fish feel more secure.

This species possesses a slender, streamlined body, perfectly suited for its active lifestyle. They almost exclusively inhabit the upper third of the water column, constantly exploring the surface. This top-dwelling behavior is a key consideration when aquascaping, as they require open swimming space in this zone. Their social structure is strictly shoaling; keeping them in insufficient numbers leads to stress and shyness. A group allows them to establish a pecking order and engage in natural social interactions. When selecting tank mates, prioritize small, peaceful species like other small tetras, rasboras, or dwarf cichlids. Avoid very large or hyperactive fish, which will cause them significant stress.

As an omnivore, providing a varied diet is crucial for their long-term health. A high-quality staple flake or micro-pellet should be supplemented regularly with live or freeze-dried foods such as daphnia and brine shrimp. This mimics the varied diet of insects and plant matter they would find in the wild. Although they have a low biological impact on the aquarium and produce minimal waste, they are sensitive to fluctuations in water chemistry. Maintaining stable, clean water through regular maintenance is key to their well-being, marking them as a species for the aquarist who can provide consistent care.

Copella arnoldi, a member of the Lebiasinidae family, is a small characin distributed throughout freshwater basins in South America. Its classification places it within a family known for its slender, pencil-like body forms and unique reproductive strategies. The species is morphologically characterized by a fusiform, or torpedo-shaped, body which is an adaptation for agile movement in the water column. This streamlined physique minimizes hydrodynamic drag, allowing for the quick bursts of speed necessary for both foraging and its remarkable reproductive leaps.

Ecologically, C. arnoldi occupies the upper strata of slow-moving aquatic environments. These habitats are typically characterized by soft, acidic water with a low mineral content and a significant presence of tannins from decaying botanical matter. Its physiology reflects these conditions, with a preference for a specific range of water chemistry. The species exhibits a moderate metabolism and comparatively low oxygen consumption, adaptations that are beneficial in warm, slow-flowing waters where dissolved oxygen levels can fluctuate. Its low waste production results in a minimal bioload factor, an important consideration in controlled aquatic systems.

Behaviorally, it is an obligate shoaling species. This social structure serves multiple purposes, including enhanced predator evasion and foraging efficiency. A notable behavioral trait is its propensity for leaping from the water, which serves as a primary escape mechanism from aquatic threats. This behavior is directly linked to its most famous characteristic: a reproductive strategy involving terrestrial egg deposition on overhanging vegetation, a complex adaptation to avoid aquatic egg predators. According to the IUCN Red List, Copella arnoldi is categorized as Least Concern (LC), indicating a stable and widespread population in its native range with no immediate conservation threats.

Breeding the Splash Tetra is considered a moderately difficult endeavor that requires specific environmental conditions to trigger their unique reproductive behavior. Success hinges on recreating the precise setup that facilitates their out-of-water spawning. A dedicated breeding aquarium with a lowered water level is the first requirement, leaving several inches of space between the water's surface and the tank lid. Broad-leafed plants like Anubias, or even a floating piece of slate or plastic secured to the glass, should be provided as an overhanging surface for egg deposition.

Sexing the fish is relatively straightforward. Males are typically larger, more intensely colored, and possess more elongated and elaborate finnage, particularly the dorsal and anal fins, compared to the smaller, plumper females. For a successful spawning attempt, a ratio of one male to two or three females is recommended to reduce aggression and distribute the male's attention.

The spawning event is a remarkable display. The conditioned pair will swim in unison beneath the chosen overhanging surface. In a coordinated leap, they will jump out of the water, attach themselves to the surface using their fins, and deposit and fertilize a small clutch of adhesive eggs in a split second before falling back into the water. This process is repeated until up to a hundred eggs are laid. Following spawning, the female's role is complete, but the male begins his parental duties. He will remain stationed beneath the eggs, using his tail to splash water onto the clutch to prevent it from desiccating. After approximately 36-48 hours, the eggs will hatch, and the fry will drop into the water. At this point, the male should be removed to prevent filial cannibalism. The minuscule fry require microscopic foods like infusoria or liquid fry food for the first few days, after which they can be transitioned to baby brine shrimp. Water quality must be kept pristine with small, frequent water changes to ensure a high survival rate.