Freshwater Needlefish
Potamorrhaphis guianensis
The Freshwater Needlefish (Potamorrhaphis guianensis) is a peaceful fish that's rewarding to keep. Give it a tank of at least 320 litres (85 US gallons), water held at 66-86°F, and a pH of 6.5-7.5.
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 litres (85 US gallons) works well. Keep the water at 66-86°F with a pH around 6.5-7.5, and set up both cover and open swimming space where they spend most of their time (Mid). They grow to around 35 cm, so plan the tank size and filtration for a full-grown adult rather than the small juvenile you see in the shop.
What Do Freshwater Needlefish Eat?
They're not fussy eaters - feed a varied diet, rotating good-quality dry, frozen, and gel foods rather than the same thing every day, and match the food size to their mouths.
Freshwater Needlefish Tank Mates
Requires a large tank and good filtration. The Freshwater Needlefish is peaceful, which is the first thing to weigh up when you choose tank mates. At around 35 cm fully grown, it needs tank mates that can hold their own against its size and appetite. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Freshwater Needlefish Good for Beginners?
Care demand varies by line and setup. Match the care level to how often you actually test and change water.
Freshwater Needlefish - frequently asked questions
What size tank do Freshwater Needlefish need?
Freshwater Needlefish need a tank of at least 320 litres (85 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
What water parameters do Freshwater Needlefish need?
Keep them at 66-86°F with a pH of 6.5-7.5, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Freshwater Needlefish eat?
Freshwater Needlefish are omnivores and aren't fussy eaters. Feed a varied mix of good-quality dry, frozen, and gel foods, and match the food size to their mouths. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Freshwater Needlefish good for beginners?
It depends on the setup. Match Freshwater Needlefish to how often you actually test water and perform maintenance.
Common mistakes with Freshwater Needlefish
- Underestimating tank size - the minimum footprint is 320 litres (85 US gallons); impulse buying into a smaller tank leads to stress and shortened lifespan.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Freshwater Needlefish
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- OscarPredator - Oscar will eat or injure smaller tank mates
- Pea PufferPredator - Pea Puffer will eat or injure smaller tank mates
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
