Rhynchitis Demonfish (Satanoperca rhynchitis)

Geographic Origin and Biotope: The Border Sifter. Species native to the river border zone between northern Brazil (Amapá) and French Guiana, mainly confined to the Oyapock River basin. Prefers calm, marginal and very warm waters, on uniform bottoms of very pure sand and silt, shielded by dense walls of riparian vegetation or hanging roots (Mixed Clearwater/Blackwater).

Taxonomy and Morphology: The "Benthic Stinger". The specific name *rhynchitis* refers to the exceptionally developed rostrum (nose/beak). Compared to the stockier *S. jurupari*, the snout is much more elongated and acute, sloping almost straight from the eyes. Massive but streamlined build, with expanded, fleshy and rubbery protrusible lips. No trace of spots on the flank.

Social Behavior: The Peaceful Tireless Worker. Deeply gregarious species (minimum 5-6 individuals); if raised singly it faces lethal wasting due to solitary phobia. Exquisitely peaceful, ignores smaller fish. Spends every single waking minute vigorously "chewing" sand and spitting it from the gills in thick clouds.

Coloration and Sexual Dimorphism: Turquoise Mask and Copper. Base body of beige, olive or pale copper (highly reflective under adequate lights). THE DIAGNOSTIC TRAIT (compared to *jurupari*): the snout, cheeks and gill cover are richly furrowed by very thick iridescent Turquoise Blue irregular dots and vermiculations. The only dark spot is a small ocellus at the root of the caudal fin. No obvious sexual dimorphism other than slightly larger sizes in old alpha males.

Tank Setup: Demands "Immense Expanses of Sugar" (Tank min. 150 cm / 60 in). THE ABSOLUTE DOGMA IS THE SANDY LAYER. Granular gravels or soils strictly forbidden: they would fatally lacerate the gills. Prepare a bed of impalpable river sand (min. 5 cm / 2 in) with wide open spaces, punctuated only by enormous polished river stones and solid branches. Plants tolerated only if tied to suspended woods; if planted, they will be regularly uprooted by the excavating fish.

Feeding and Diet: Peaceful Omnivorous Micro-Siphon. Continuous benthic diet. Will eat exclusively from the bottom: crumbly sinking cichlid pellets, daphnia, brine shrimp and frozen bloodworms. The meal must sink into the sand, forcing them to chew earth and food simultaneously for proper gastric emptying and psychological well-being.

Water Quality: Need for Strict Hygiene and Heat. Moderately resistant if kept in a thick school, succumbs tragically to high nitrates. DEMANDS high tropical aquarium temperatures (26-29°C / 79-84°F), soft to medium water (GH 1-6) and generally acidic pH (5.5 - 7.0). Powerful (Sump) but not turbulent filtration, coupled with mandatory 40-50% weekly water changes by siphoning the bottom.

Compatibility and Cohabitation: Serene Community of Calm Rivers. Perfect tankmate for the peaceful. Excellent in schools paired with small-medium swimmers (Tetras, Hemigrammus, Pencilfish), large calm fish like Severum or Uaru, and resistant loricariids (Ancistrus, Peckoltia). Strictly forbidden large territorial Corydoras (harmful competition) or aggressive South/Central American cichlids that would skin them alive.

Aquarium Reproduction: Protective Immediate Mouthbrooders. Similar to *S. jurupari*, very fascinating in a mature group. The female lays adhesive eggs on stones or clean hard dry foliage and, unlike larvophilic species, AFTER A FEW HOURS OR DAYS OF FERTILIZATION collects all the eggs/larvae directly into the immense throat sac, mouthbrooding for dozens of days and spitting out the somewhat grown free swimmers only to feed, under the martial escort of the male. Rare to see without a dedicated tank.

Risks and Diseases: Neotropical Bloat Lethality and Oral Cuts. Rearing on rough bottoms will cause an internal necrotic gill excoriation with subsequent fatal purulent facial paresis. Highly subject to Hole in the Head (Cranial ulcerous holes from Hexamita/Toxic mineral deficiency) and paralyzing starvation if housing does not respect the strict thermal, chemical and social changes described.