Fathead minnow

Pimephales promelas

Also known as Rosy red minnow

FreshwaterFish

Fathead minnow (Pimephales promelas) — Dhester88 · CC BY-SA 4.0

Care at a glance

Temperature: 50–72°F (10–22°C)
pH: 6.5–8.0
Adult size: 3 in (7.5 cm)
Minimum tank: 20 gal (75 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Bottom
Difficulty: Easy
Breeding: Medium
Rarity: Common
Origin: North America
Family: Cyprinidae

Overview

Keep them in a group, since they are peaceful schoolers that mostly work the lower part of the tank. They are about as easygoing as fish get and will eat flake, pellets, and frozen or live foods without complaint. The main thing is to keep them cool, as they do poorly in warm tropical tanks over the long run. A 75 liter tank gives a small group plenty of room.

In the wild

Fathead minnows are a hardy North American fish found in ponds, ditches, and slow streams, often in murky or low-oxygen water that defeats fussier species. They tolerate a wide range of conditions. In the aquarium they want cool water, roughly 10 to 22 C, so keep them unheated, and they accept pH from 6.5 to 8. A simple tank with some plants and a sandy or fine gravel bottom suits them fine.

Good to know

A small cyprinid in the family Cyprinidae, reaching about 7.5 cm. Breeding males turn dark, develop a fleshy pad on the back, and grow rows of bumps called breeding tubercles on the snout. The male guards eggs laid on the underside of a flat surface, which is unusual care for a minnow. The orange and gold aquarium strain sold as the rosy red minnow is a color form of this same species.

Did you know

Fathead minnows release an alarm substance from their skin when injured, and nearby fish smell it and immediately scatter or freeze. This chemical warning system is so reliable that researchers use the species as a standard test animal for water pollution studies.