Girl in the Goldfish Bowl, Crucible Studio, Sheffield

So realistic is Ultz's design for Girl in the Goldfish Bowl that you feel in need of a snorkel and flippers.

So realistic is Ultz's design for Girl in the Goldfish Bowl that you feel in need of a snorkel and flippers. In front of a gigantic, turquoise shower curtain, air bubbles escape up two watery columns, fronds from green ferns droop over the pebble-dashed floor and all the action is contained within an oblong square; a fish tank, in fact.

Among the flotsam and jetsam surfacing in the Canadian Morris Panych's whimsical play, receiving its European premiere in a fluid production by David Newman, a mysterious merman becomes the object of Iris's attention. She is "nearly 11", and her mind is overflowing with half-understood facts about everything from sex and the Cuban missile crisis - then reaching its climax - to the shaky condition of her parent's marriage and the state of the Latin mass. From the perspective of adulthood, Iris's memories have become clouded, the past skewed like the world observed through the convex glass of a goldfish bowl. It's clear enough, though, that things aren't going great in the boarding-house run by her parents, Owen and Sylvia; they're definitely drowning, not waving. Her mother told Iris she'd know when she was grown up, at the moment "you stop being happy and start remembering how you used to be".

How she used to be is too clever by half; a gawky girl enthusiastically portrayed here by Kirsty Bushell. Iris convinces herself that her pet goldfish, which her mother flushed down the lavatory, has been reincarnated as the dripping stranger she welcomes into the family home. The mysterious Mr Lawrence (Ferdy Roberts) wears his amphibian air lightly, gradually transforming from whiskery mole-like nervousness to something more sympathetic.

His presence at first disorientates, then seduces and finally cements relations within the household. Iris's bored mother, on the point of leaving her husband when she inconveniently falls and breaks her arm, falls next for Mr Lawrence. Iris's father, whose wartime injuries have left him unable to focus on much except his geometric doodlings, wants to keep Mr Lawrence there in order to hold on to his wife. And Iris wants to preserve Mr Lawrence in order to feed her piscine fantasy. Miss Rose, the lodger, whose life is stuck in a pre-war void, cans fish in a factory by day and tries to net men by night, filling any remaining time with some energetic sipping.

Panych (the Grey-haired Man in a handful of X-Files episodes) sometimes flounders, his quirky lines not quite disguising the fact that there's too little depth to his story and too little flesh on his characters. But if Girl in the Goldfish Bowl doesn't quite hit the mark, it gets close enough to provoke moments of laughter in the course of its fishy business.

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