Northern Studfish

Fundulus catenatus

Northern Studfish (Fundulus catenatus) — Varies care, Peaceful, under Other. Minimum tank in the app: 37 US gal min; aim for 59–77°F and pH 6.5–7.5. The Northern Studfish is an intriguing choice for aquarists seeking a mid-water swimmer with semi-aggressive tendencies.

Northern Studfish (Fundulus catenatus) in a planted freshwater aquarium
Care levelVaries
TemperamentPeaceful
Min tank size37 US gal min
pH range6.5–7.5
Temperature59–77°F
Max size5.9 in (15.0 cm)
Captive lifespan2–4 years
SchoolingNo

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

To optimize tank dynamics, provide a balance of open swimming space and dense cover using plants and driftwood. Aim for moderate water flow to encourage natural swimming patterns, and select a substrate that supports plant growth while allowing for easy maintenance. Proper lighting can enhance their colors, but avoid overly bright setups that may increase stress.

What Do Northern Studfishs Eat?

As omnivores, they feed at a moderate pace, and competition can arise if kept with faster, more assertive feeders. Offering a varied diet that includes high-quality flakes, live, or frozen foods can enhance their health and coloration, but monitor to ensure all individuals receive adequate nutrition.

Northern Studfish Tank Mates

Ideal tank mates include moderately sized, non-territorial species that occupy different swimming levels. Avoid pairing with overly aggressive or small fish that may provoke stress or become targets. Intraspecies interactions are generally peaceful, but maintaining a varied environment can prevent potential squabbles over territory.

Are Northern Studfishs Good for Beginners?

Care demand varies with setup and individual fish; use the numbers above as your baseline. Aquarists often underestimate the Northern Studfish's need for space and structure, leading to stress and aggression. Overcrowding or poor tank design can result in territorial disputes and reduced well-being, so it's crucial to follow recommended stocking guidelines and provide ample hiding spots.

Building a community? Run the full list through the stocking calculator before you add anything else.

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