SB 8.24.44

so 'nudhyātas tato rājñā
prādurāsīn mahārṇave
eka-śṛṅga-dharo matsyo
haimo niyuta-yojanaḥ

saḥ—the Lord; anudhyātaḥ—being meditated upon; tataḥ—thereafter (hearing the words of the saintly brāhmaṇas); rājñā—by the King; prādurāsīt—appeared (before him); mahā-arṇave—in the great ocean of inundation; eka-śṛṅga-dharaḥ—with one horn; matsyaḥ—a big fish; haimaḥ—made of gold; niyuta-yojanaḥ—eight million miles long.

Then, while the King constantly meditated upon the Supreme Personality of Godhead, a large golden fish appeared in the ocean of inundation. The fish had one horn and was eight million miles long.