Six-line wrasse

Geographical Origin & Biotope:

The Six Line Wrasse (*Pseudocheilinus hexataenia*) is a highly active, aggressively territorial marine teleost natively endemic to the warm, shallow, and highly complex coral reefs of the Indo-Pacific Ocean. Their natural biotope is defined by densely packed, branching stony corals (*Acropora* and *Pocillopora* thickets) and seaward reef margins, where they tirelessly weave through tight branches to hunt for microscopic, parasitic benthic invertebrates.

Taxonomy & Morphology:

Scientifically classified within the Labridae (Wrasse) family, they belong to the *Pseudocheilinus* genus, known for their compact size and immense attitude. Fully mature adults are small, reaching only 7.0 to 8.0 centimeters (2.8-3.1 inches) in length. They possess a classic, torpedo-shaped body designed for supreme agility in tight spaces. They possess distinctive, independently moving eyes that constantly scan the rockwork for the slightest movement of tiny crustacean prey.

Social Behavior:

They are hyper-active, highly diurnal, and notoriously belligerent micro-predators. They spend their entire day in a state of rapid, perpetual motion, meticulously darting in and out of the live rock. Unlike *Halichoeres* wrasses, they DO NOT sleep in the sand. Instead, at night, they spin a thick, protective mucus cocoon deep within a rock crevice, which masks their scent from nocturnal predators. They are fiercely territorial and completely intolerant of other Wrasses.

Coloration & Sexual Dimorphism:

Sexual dimorphism is visually non-existent. Their coloration is incredibly striking and intricate. The body is a deep, saturated purplish-blue, violently overlaid with six distinct, horizontal, vibrant neon orange stripes extending from the gills to the tail base. The caudal fin (tail) is a stark, solid emerald green, marked with a prominent, false "eye-spot" (ocellus) on the upper edge to confuse predators. Their massive eyes are strikingly bright red.

Tank Setup:

The aquarium architecture MUST accommodate their hyper-active swimming and need for hunting grounds. A minimum 110-liter (30-gallon) marine aquarium is required. CRITICAL REQUIREMENT: The tank MUST be densely aquascaped with massive amounts of complex, porous live rock. They require an endless labyrinth of crevices to hunt copepods and establish territory. Without complex rockwork to distract them, their aggression toward tankmates will multiply exponentially.

Diet & Feeding:

They are obligate, continuous micro-carnivores with a voracious appetite. In the wild, they are highly beneficial, constantly plucking parasitic flatworms and tiny pyramidellid snails off corals. In the aquarium, they MUST be fed a highly varied, meaty diet 2-3 times daily (Mysis shrimp, enriched brine shrimp). CRITICAL WARNING: They are hyper-efficient hunters and will rapidly decimate the tank's entire copepod population, starving out delicate fish like Mandarins.

Water Quality:

Originating from pristine Indo-Pacific reefs, they are incredibly hardy, highly resilient to poor water quality, and famously disease-resistant due to their thick slime coat. They demand stable tropical heat (24-27°C / 75-81°F). Specific gravity (salinity) MUST be maintained precisely between 1.020 and 1.025. They require hard, highly alkaline water (pH 8.1 - 8.4) and a well-oxygenated environment. They thrive in moderate to strong, turbulent water flow.

Compatibility & Tankmates:

Compatibility requires extreme caution due to their vicious territoriality. They are 100% reef-safe and excellent pest controllers. CRITICAL WARNING: Despite their small size, they are absolute terrors. They will violently harass and kill peaceful, slow-moving fish (Mandarins, Firefish, small Gobies) and absolutely CANNOT be kept with other Wrasses. They MUST be the absolute LAST fish added to the aquarium, and only housed with robust, semi-aggressive tankmates (Tangs, Angelfish).

Aquarium Breeding:

Breeding the Six Line Wrasse in captivity has occasionally been achieved in highly specialized commercial facilities, but never by home aquarists. They are protogynous hermaphrodites; the most dominant female in a group will change sex to become the male. They are pelagic spawners, performing a rapid upward spawning ascent at dusk to release microscopic eggs into the current. Rearing the larvae requires complex, multi-stage, industrial-scale plankton culturing.

Risks & Diseases:

The absolute greatest physical risk is lethal aggression; aquarists frequently add them to control flatworms, only to watch the Six Line systematically hunt and kill every other small, peaceful fish in the tank. Always introduce them last. The second major risk is lethal desiccation; they are incredibly powerful jumpers. A completely tight-fitting lid or mesh screen is unconditionally mandatory. Medically, they are highly robust and rarely succumb to Marine Ich.