207. WITH RESPECT TO THE FOOD OF FISHES, this is almost universally found in their own element. They are mostly carnivorous, though they seize upon almost anything that comes in their way: they even devour their own offspring, and manifest a particular predilection for all living creatures. Those, to which Nature has meted out mouths of the greatest capacity, would seem to pursue everything with life, and frequently engage in fierce conflicts with their prey. The animal with the largest mouth is usually the victor; and he has no sooner conquered his foe than he devours him. Innumerable shoals of one species pursue those of another, with a ferocity which draws them from the pole to the equator, through all the varying temperatures and depths of their boundless domain. In these pursuits a scene of universal violence is the result; and many species must have become extinct, had not Nature accurately proportioned the means of escape, the production, and the numbers, to the extent and variety of the danger to which they are exposed. Hence the smaller species are not only more numerous, but more productive than the larger; whilst their instinct leads them in search of food and safety near the shores, where, from the shallowness of the waters, many of their foes are unable to follow them.
208. THE FECUNDITY OF FISHES has been the wonder of every natural philosopher whose attention has been attracted to the subject. They are in general oviparous, or egg-producing; but there are a few, such as the eel and the blenny, which are viviparous, or produce their young alive. The males have the _milt_ and the females the _roe_; but some individuals, as the sturgeon and the cod tribes, are said to contain both. The greater number deposit their spawn in the sand or gravel; but some of those which dwell in the depths of the ocean attach their eggs to sea-weeds. In every instance, however, their fruitfulness far surpasses that of any other race of animals. According to Lewenhoeck, the cod annually spawns upwards of nine millions of eggs, contained in a single roe. The flounder produces one million; the mackerel above five hundred thousand; a herring of a moderate size at least ten thousand; a carp fourteen inches in length, according to Petit, contained two hundred and sixty-two thousand two hundred and twenty-four; a perch deposited three hundred and eighty thousand six hundred and forty; and a female sturgeon seven millions six hundred and fifty-three thousand two hundred. The viviparous species are by no means so prolific; yet the blenny brings forth two or three hundred at a time, which commence sporting together round their parent the moment they have come into existence.