Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 19
यथा स्वयंवरे राज्ञि मत्स्य: पार्थेप्सया कृत: ।अयं तु बहिराच्छन्नो दृश्यते स जले परम् ॥ १९ ॥
yathā svayaṁ-vare rājñimatsyaḥ pārthepsayā kṛtaḥayaṁ tu bahir ācchannodṛśyate sa jale param
Just as a fish was used as a target in your svayaṁvara ceremony, O Queen, to assure that you would obtain Arjuna as your husband, so a fish was also used in my ceremony. In my case, however, it was concealed on all sides, and only its reflection could be seen in a pot of water below.
Arjuna is famous as the most expert bowman. Why, then, could he not hit the fish target at Śrīmatī Lakṣmaṇā’s svayaṁvara ceremony just as he had done once before to win Draupadī? Śrīla Śrīdhara Svāmī explains: The target at Draupadī’s svayaṁvara had been covered only partially, so that a marksman could see it if he looked straight up the pillar on which it was placed. To shoot Lakṣmaṇā’s target, however, it was necessary to aim by looking up and down at the same time, an impossible feat for any mortal. Therefore only Kṛṣṇa could strike the target.