Mahabharata Adi Parva Chapter 63:3

Mahabharata Adi Parva Chapter 63:3 'And Girika, the wife of Vasu, after her menstrual course, purifying herself by a bath, represented her state unto her lord. But that very day the Pitris of Vasu came unto that best of monarchs and foremost of wise men, and asked him to slay deer (for their Sraddha). And the king, thinking that the command of the Pitris should not be disobeyed, went a-hunting thinking of Girika alone who was gifted with great beauty and like unto another Sri herself. And the season being the spring, the woods within which the king was roaming, had become delightful like unto the gardens of the king of the Gandharvas himself. There were Asokas and Champakas and Chutas and Atimuktas in abundance: and there were Punnagas and Karnikaras and Vakulas and Divya Patalas and Patalas and Narikelas and Chandanas and Arjunas and similar other beautiful and sacred trees resplendent with fragrant flowers and sweet fruits. And the whole forest was maddened by the sweet notes of the kokila and echoed with the hum of maddened bees. And the king became possessed with desire, and he saw not his wife before him. Maddened by desire he was roaming hither and thither, when he saw a beautiful Asoka decked with dense foliage, its branches covered with flowers. And the king sat at his ease in the shade of that tree. And excited by the fragrance of the season and the charming odours of the flowers around, and excited also by the delicious breeze, the king could not keep his mind away from the thought of the beautiful Girika. And beholding that a swift hawk was resting very near to him, the king, acquainted with the subtle truths of Dharma and Artha, went unto him and said, 'Amiable one, carry thou this seed (semen) for my wife Girika and give it unto her. Her season hath arrived.' "The hawk, swift of speed, took it from the king and rapidly coursed through the air. While thus passing, the hawk was seen by another of his species. Thinking that the first one was carrying meat, the second one flew at him. The two fought with each other in the sky with their beaks. While they were fighting, the seed fell into the waters of the Yamuna. And in those waters dwelt an Apsara of the higher rank, known by the name of Adrika, transformed by a Brahmana's curse into a fish. As soon as Vasu's seed fell into the water from the claws of the hawk, Adrika rapidly approached and swallowed it at once. That fish was, some time after, caught by the fishermen. And it was the tenth month of the fish's having swallowed the seed. From the stomach of that fish came out a male and a female child of human form. The fishermen wondered much, and wending unto king Uparichara (for they were his subjects) told him all. They said, 'O king, these two beings of human shape have been found in the body of a fish!' The male child amongst the two was taken by Uparichara. That child afterwards became the virtuous and truthful monarch Matsya.