Every creature that swims, whether it skims on the surface of the waters, or cleaves the depths, is of the nature of a moving creature, LXX. creeping. since it drags itself on the body of the water.  Certain aquatic animals have feet and walk; especially amphibia, such as seals, crabs, crocodiles, river horses Basil uses the classical greek form οἱ ποτάμιοι ἵπποι, as in Herod. and Arist.  The dog-Greek hippopotamus, properly a horse-river, is first found in Galen. and frogs; but they are above all gifted with the power of swimming.  Thus it is said, Let the waters produce moving creatures.  In these few words what species is omitted?  Which is not included in the command of the Creator?  Do we not see viviparous animals, seals, dolphins, rays and all cartilaginous animals?  Do we not see oviparous animals comprising every sort of fish, those which have a skin and those which have scales, those which have fins and those which have not?  This command has only required one word, even less than a word, a sign, a motion of the divine will, and it has such a wide sense that it includes all the varieties and all the families of fish.  To review them all would be to undertake to count the waves of the ocean or to measure its waters in the hollow of the hand.  “Let the waters produce moving creatures.”  That is to say, those which people the high seas and those which love the shores; those which inhabit the depths and those which attach themselves to rocks; those which are gregarious and those which live dispersed, the cetaceous, the huge, and the tiny.  It is from the same power, the same command, that all, small and great receive their existence.  “Let the waters bring forth.”  These words show you the natural affinity of animals which swim in the water; thus, fish, when drawn out of the water, quickly die, because they have no respiration such as could attract our air and water is their element, as air is that of terrestrial animals.  The reason for it is clear.  With us the lung, that porous and spongy portion of the inward parts which receives air by the dilatation of the chest, disperses and cools interior warmth; in fish the motion of the gills, which open and shut by turns to take in and to eject the water, takes the place of respiration. cf. Arist., De Part. Anim. iii. 6. διόπερ τῶν μὲν ἰχθύων οὐδεὶς ἔχει πνεύμονα ἀλλ᾽ ἀντὶ τούτου βράγχια καθάπερ εἴρηται ἐν τοῖς περὶ ἀναπνοῆς· ὕδατι γᾶρ ποιεῖται τὴν κατάψυξιν, τὰ δ᾽ ἀναπνέοντα ἔχει πνεύμονα ἀναπνεῖ δὲ τὰ πεζὰ πάντα.  Fish have a peculiar lot, a special nature, a nourishment of their own, a life apart.  Thus they cannot be tamed and cannot bear the touch of a man’s hand. Here Basil is curiously in contradiction to ancient as well as modern experience.  Martial’s epigram on Domitian’s tame fish, “qui norunt dominum, manumque lambunt illam qua nihil est in orbe majus” (iv. 30) is illustrated by the same author’s “natat ad magistrum delicata muræna” (x. 30), as well as by Ælian (De animal. viii. 4).  “Apud Baulos in parte Baiana piscinam habuit Hortensius orator, in qua murænam adeo dilexit ut exanimatam flesse credatur:  in eadem villa Antonia Drusi murænæ quam diligebat inaures addidit.”  Plin. ix. 71.  So Lucian οὗτοι δε (ίχθύες) καὶ ὀνόματα ἔχουσι καὶ ἔρχονται καλούμενοι.  (De Syr. Dea. 45.)  John Evelyn (Dairy 1644) writes of Fontainebleau:  “The carps come familiarly to hand.”  There was recently a tame carp at Azay le Rideau.