Wilder's mouse catfish

Hassar wilderi

Also known as Mouse cat

FreshwaterFish

Care at a glance

Temperature: 73–82°F (23–28°C)
pH: 6.0–7.5
Adult size: 9.8 in (25 cm)
Minimum tank: 106 gal (400 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Bottom
Difficulty: Medium
Breeding: No record
Rarity: Rare
Origin: Tocantins and Araguaia basins, Brazil
Family: Doradidae

Overview

A slim, active, sand-sifting catfish that shoals in the wild, so keep a group of at least four to six and give them open bottom space to cruise. Despite the mouse name they reach a fair size, and they stay peaceful, working the sand together and ignoring any tankmate too large to be eaten. They need a soft sand bed to sift, gentle current, and some wood for shade at the edges. Feed sinking pellets, wafers, and frozen foods, making sure enough settles onto the sand. A group needs a tank of around 400 liters, with more length better as they grow.

In the wild

Hassar wilderi lives in the Tocantins and Araguaia drainages of Brazil, where it shoals over beds of fine sand in the flowing main channels of the rivers. Recreate that with a soft sand substrate, open swimming room, moderate current, and clean, well-oxygenated water. Keep it warm at 23-28 C and soft to neutral, around pH 6-7.5. A few pieces of driftwood at the sides give the group somewhere to shelter without breaking up the open floor.

Good to know

Described by Kindle in 1895, this thorny catfish of the family Doradidae reaches about 25 cm and is built as a sand-sifter, with a long, downturned snout and trailing barbels. It belongs to the genus Hassar, a group of slender, shoaling doradids of fast-flowing river channels. Like its relatives it wears hooked flank scutes and can stridulate its pectoral spines. Aquarium breeding is not on record.

Did you know

The mouse name describes its habits, not its size: it nibbles constantly at the sand, sifting the grains for small prey while the shoal drifts slowly forward together over the river bed.

Tank mates

Wilder's mouse catfish is a peaceful, schooling species that keeps to the bottom. These picks match on water type, temperature, pH, size and temperament.