Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 37

Sanskrit:

नैवाविदन् क्षीयमाणं जलं गाधजलेचरा: ।यथायुरन्वहं क्षय्यं नरा मूढा: कुटुम्बिन: ॥ ३७ ॥

ITRANS:

naivāvidan kṣīyamāṇaṁjalaṁ gādha-jale-carāḥyathāyur anv-ahaṁ kṣayyaṁnarā mūḍhāḥ kuṭumbinaḥ

Translation:

The fish swimming in the increasingly shallow water did not at all understand that the water was diminishing, just as foolish family men cannot see how the time they have left to live is diminishing with every passing day.

Purport:

After the rainy season the water gradually goes down, but stupid fish do not understand this; thus they are often stranded on the lakeshores and riverbanks. Similarly, those infatuated with family life do not understand that the remainder of their life is constantly decreasing; thus they fail to perfect their Kṛṣṇa consciousness and are stranded in the cycle of birth and death.