Chapter XV.

1. It has already been observed that fish migrate from the deep water to the coast, and from the coast to the deep water, in order to avoid the excesses of cold and heat. Those that frequent the neighbourhood of the coast are better than those from deep water, for the feeding grounds are better and more abundant. For wherever the sun strikes the plants are more frequent, and superior, and more delicate, as in gardens, and the black shore-weed grows near the land, and the other kinds rather resemble uncultivated plants. The neighbourhood of the coast is also more temperate, both in heat and cold, than the rest of the sea; for which reason the flesh of fish which live near the shore is more compact, while that of fish from deep sea is watery and soft. The sinodon, cantharus, orphos, chrysophrys, cestreus, trigla, cichla, dracon, callionymus, cobius, and all the rock fish live near the shore. The trygon, selache, the white congers, the channa, erythrinus, and glaucus inhabit deep water. The phagrus, scorpius, the black conger, the muræna, and coccyx occupy either situation indifferently.

2. They vary also in different places; as in the neighbourhood of Crete the cobius and all the rock fish are fat. The tunny also becomes good again after Arcturus, for it is not tormented by the œstrus after that period; for which reason also it is inferior during the summer. In lakes near the sea also there are several kinds of fish, as the salpa, chrysophrys, trigla, and nearly all the rest. The amia also is found in such situations as in the vicinity of Alopeconnesus, and in the lake of Bistonis there are many fish. Many of the coliæ do not enter the Pontus; but they pass the summer and rear their young in the Propontis, and winter in the Ægean. The thynnus, pelamis, and amia enter the Pontus in the spring and pass the summer there, and so do nearly all the rhyades and the gregarious fish. Many fish are gregarious, and gregarious fish have a leader of the shoal.

3. They all enter the Pontus for the sake of the food (for the pasture is more abundant and superior, on account of the fresh water), and for fear of the large creatures, which are smaller there; and except the phocona and dolphin, there is no other found in the Pontus; and the dolphin is small, but when we leave the Pontus we find a larger dolphin. They enter this sea for the sake of food and rearing their young; for the situation is better for this purpose, and the fresh sweet water nourishes the young fry. When they have reared their young, and the fry begin to grow, they migrate immediately after the Pleiades. If the south wind blow during the winter, they leave the place more slowly; but with a north wind they swim faster, for then the wind helps them along. The small fry is captured in the neighbourhood of Byzantium, for they make no long stay in the Pontus.

4. The other fish are seen both in their egress and ingress. The trichia is only seen as it enters, and is not observed to leave again; and if one is captured at Byzantium, the fishermen purify their nets, for it is unusual for them to return. The reason is this: these are the only fish that swim up into the Ister, and when this river divides they swim down into the Adriatic. The following is a proof; for the converse happens here, and they are never captured entering the Adriatic, but as they leave it.

5. The tunnies, as they enter, swim with their right side to the shore, and leave with their left side to the shore; and some persons say that they do this because they see better with their right eye, and their sight is naturally dim. The rhyades move during the day, and in the night remain quiet and feed, unless the moon is bright, in which case they continue their journey and do not rest themselves. And some persons engaged about the sea say that after the winter solstice they do not move, but remain quiet wherever they may be till the equinox.

6. The coliæ are taken as they enter, but not as they return. The best are taken in the Propontis before the breeding season. The other rhyades are captured more frequently as they leave the Pontus, and are then in perfection. Those that swim near the shore are the fattest when captured; and the farther they are away, the more lean they are; and frequently, when the south wind blows, they swim out in company with the coliæ and mackerel, and are taken lower down rather than at Byzantium. This is the nature of their migrations.