An initial localized eddy was generated in a rotating tank by a source–sink method to study the behaviour of an isolated barotropic eddy on a β-plane. The evolution of the eddy was compared with the laboratory experiments by Firing & Beardsley (1976) and by Takematsu & Kita (1985, 1988), confirming the northwestward (southwestward) translation of a cyclonic (anticyclonic) isolated eddy due to nonlinear effects. Anticyclonic eddies were contrasted with cyclonic eddies in the tank experiment, showing a cyclonic–anticyclonic asymmetry due to the topographic β as a substitute for the planetary β. The fluid experiment was simulated well by numerical simulation based on the quasi-geostrophic vorticity equation. Numerical experiments verified the northwestward (southwestward) translation both for an initially Gaussian and initially Rankine-type isolated cyclonic (anticyclonic) eddy.