Northern Studfish

Fundulus catenatus

FreshwaterFish

Care at a glance

Temperature: 59–77°F (15–25°C)
pH: 6.5–8.0
Adult size: 5.9 in (15 cm)
Minimum tank: 37 gal (140 L)
Temperament: Mostly peaceful
Social behavior: Social
Swim level: Middle
Difficulty: Difficult
Breeding: No record
Rarity: Very rare
Origin: United States
Family: Fundulidae

Overview

The northern studfish is a large, active topminnow that does best in a group in a long, roomy tank, where males show off strong blue and orange breeding color. Males display and spar, so give them space and line-of-sight breaks rather than a cramped tank. Feed generously on live and frozen foods such as bloodworms, blackworms, crickets and brine shrimp, with some flake and pellet accepted. It swims through the middle and upper water and likes clean, well oxygenated conditions. Because adults reach a good size, a tank of 140 liters or larger is the sensible minimum for a small group.

In the wild

Northern studfish live in clear, permanently flowing upland streams in the central United States, keeping to shallow margins over clean sand, gravel and rock. The water there is cool and well oxygenated for much of the year. In the aquarium, give them open swimming room, a sand or fine gravel bottom, some current and cool to moderate temperatures between about 15 and 25 C. A near-neutral to slightly alkaline pH from roughly 6.5 to 8 fits their stream origins, and steady water movement keeps them in good condition.

Good to know

The northern studfish belongs to the topminnow family Fundulidae and is one of the larger members, reaching about 15 cm. Breeding males are boldly marked with blue bodies and red-brown spotting. Unlike most topminnows, which lay their eggs on plants, this species spawns over clean gravel in shallow stream edges, with no parental care afterward. Its aquarium breeding is little recorded, partly because of the space a group of these big, lively fish needs.

Did you know

Most topminnows glue their eggs to plants, but the northern studfish breaks the pattern and spawns over open gravel in the shallow edges of streams, where males in blue and rusty-orange courting color compete for the best patches.