Northern Studfish
Fundulus catenatus
The Northern Studfish (Fundulus catenatus) is a peaceful fish that's rewarding to keep. Give it a tank of at least 140 litres (37 US gallons), water held at 59-77°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
North America
- Central America & Mexico
Regional colours match the stocking calculator's origin map.
Northern Studfish Tank Setup
A tank of at least 140 litres (37 US gallons) works well. Keep the water at 59-77°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 reach about 15 cm as adults, so don't be misled by the small juveniles sold in stores.
What Do Northern Studfish 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.
Northern Studfish Tank Mates
The Northern Studfish is peaceful, which is the first thing to weigh up when you choose tank mates. Good matches come down to the whole stocking list working together - temperature, tank size, and temperament - not any single label. 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 Northern Studfish Good for Beginners?
Care demand varies by line and setup. Match the care level to how often you actually test and change water.
Northern Studfish - frequently asked questions
What size tank do Northern Studfish need?
Northern Studfish need a tank of at least 140 litres (37 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 Northern Studfish need?
Keep them at 59-77°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 Northern Studfish eat?
Northern Studfish 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 Northern Studfish good for beginners?
It depends on the setup. Match Northern Studfish to how often you actually test water and perform maintenance.
Common mistakes with Northern Studfish
- Underestimating tank size - the minimum footprint is 140 litres (37 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 Northern Studfish
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
- AxolotlPredator - Axolotl will eat or injure smaller tank mates
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
