lit. the fish and the bear's paw, you can't have both at the same time (idiom, from Mencius); fig. you must choose one or the other; you can't always get everything you want; you can't have your cake and eat it
trad. 魚與熊掌不可兼得
Also written 魚與熊掌不可兼得【yú yǔ xióng zhǎng bù kě jiān dé】