Surah Al-Kahf 18:61

فَلَمَّا بَلَغَا مَجْمَعَ بَيْنِهِمَا نَسِيَا حُوتَهُمَا فَٱتَّخَذَ سَبِيلَهُۥ فِى ٱلْبَحْرِ سَرَبًا

But when they reached the junction between them, they forgot their fish, and it took its course into the sea, slipping away.

Translation: Saheeh International

Tafsir

So when they reached a juncture between the two between the two seas they forgot their fish — Joshua forgot his luggage leaving it behind at the moment of departure and Moses forgot to remind him — and so it the fish made its way into the sea that is it formed it — through God’s forming it — by burrowing that is like …

Excerpt from Tafsir al-Jalalayn, commentary on 18:61, via Quran.com. The reader has the full commentary and 9 more tafsirs.