Walleye

Sander vitreus, the Walleye, is the largest member of the perch family native to North America and one of the continent's premier freshwater sport fish. Its distinctive tapetum lucidum gives the eyes a glassy, opaque appearance that aids vision in low-light and turbid conditions, making it an exceptionally effective twilight and nocturnal predator. Its olive-gold body is mottled with brassy flecks and it has a characteristic white tip on the lower caudal lobe.

In the aquarium, Walleye are best considered a pond or public-aquarium fish rather than a home aquarium species, given their eventual size and their need for cold, highly oxygenated water. Juveniles can be maintained in very large cold-water aquaria — 1000 litres and above — but adults outgrow even the most ambitious home setups. They require live or fresh meaty foods and are reluctant to accept prepared diets.

For serious native fish collectors with appropriate facilities and cool-water infrastructure, Walleye are fascinating display animals with an unmistakable presence. Their sensitivity to warm water and low oxygen means that water quality and temperature must be maintained with precision.

Water: 10–20 °C, pH 7.0–8.5, hard, crystal-clear water; very high oxygen demand — strong aeration essential. Tank: 1000 L absolute minimum for juveniles; prefer ponds or public display tanks for adults. Feeding: Live fish, fresh cut fish, large earthworms; difficult to transition to dead or prepared food. Breeding: Not practical in home aquaria; requires large cold-water ponds for seasonal spawning. Compatibility: Will consume any fish that fits in its mouth; keep singly or with very large robust species.