Freshwater Needlefish
Potamorrhaphis guianensis
Freshwater Needlefish (Potamorrhaphis guianensis) — Varies care, Peaceful, under Other. Minimum tank in the app: 85 US gal min; aim for 66–86°F and pH 6.5–7.5. The Freshwater Needlefish is an intriguing choice for aquarists looking to add an agile predator to their tank, but it demands ample space and excellent filtration to thrive.

Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
South America
- South America
Regional colours match the stocking calculator’s origin map.
Freshwater Needlefish Tank Setup
A tank of at least 320 liters is essential, focusing on open swimming space complemented by strategic placements of driftwood and rocks for shelter. Maintain moderate to strong water flow to mimic its natural habitat, and consider using subdued lighting to create a comfortable atmosphere that encourages active behaviour without overwhelming the fish.
What Do Freshwater Needlefishs Eat?
Being an omnivore, the Needlefish has a varied diet, but it feeds quickly and may outcompete slower eaters for food. Offering a mix of high-quality flakes, pellets, and occasional live or frozen foods can enhance its colour and vitality.
Freshwater Needlefish Tank Mates
Ideal tank mates include similarly sized, semi-aggressive fish that occupy different swimming zones, such as larger barbs or certain cichlids. Caution is advised with overly passive species, as the Needlefish may exhibit aggression if it feels threatened or crowded. Intraspecies interactions are minimal, as it does not shoal; one is usually sufficient to avoid territorial disputes.
Are Freshwater Needlefishs Good for Beginners?
Care demand varies with setup and individual fish; use the numbers above as your baseline. Aquarists often underestimate the space and filtration requirements for this species, leading to poor water quality and stress. selecting tank mates without considering size and temperament can result in aggression, causing harm to more delicate or slower fish.
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