The class of fishes which possess this power are chiefly those with labyrinthiform pharyngeal bones, so disposed in plates and cells as to retain a supply of moisture, which, whilst crawling on land, gradually exudes so as to keep the gills damp.[1]
1: CUVIER and VALENCIENNES, Hist. Nat. des Poissons, tom. vii. p. 246.
The individual which is most frequently seen in these excursions in Ceylon is a perch called by the Singhalese Kavaya or Kawhy-ya, and by the Tamils Pannei-eri, or Sennal. It is closely allied to, if not identical with, the Anabas scandens of Cuvier, the Perca scandens of Daldorf. It grows to about six inches in length, the head round and covered with scales, and the edges of the gill-covers strongly denticulated. Aided by the apparatus already adverted to in its head, this little creature issues boldly from its native pools and addresses itself to its toilsome march generally at night or in the early morning, whilst the grass is still damp with the dew; but in its distress it is sometimes compelled to travel by day, and Mr. E.L. Layard on one occasion encountered a number of them travelling along a hot and dusty gravel road under the midday sun.[1]
1: Annals and Mag. of Nat. Hist., May, 1853, p. 390. Mr. Morris, the government-agent of Trincomalie, writing to me on this subject in 1856, says—"I was lately on duty inspecting the bund of a large tank at Nade-cadua, which, being out of repair, the remaining water was confined in a small hollow in the otherwise dry bed. Whilst there heavy rain came on, and, as we stood on the high ground, we observed a pelican on the margin of the shallow pool gorging himself; our people went towards him and raised a cry of fish! fish! We hurried down, and found numbers of fish struggling upwards through the grass in the rills formed by the trickling of the rain. There was scarcely water enough to cover them, but nevertheless they made rapid progress up the bank, on which our followers collected about two bushels of them at a distance of forty yards from the tank. They were forcing their way up the knoll, and, had they not been intercepted first by the pelican and afterwards by ourselves, they would in a few minutes have gained the highest point and descended on the other side into a pool which formed another portion of the tank. They were chub, the same as are found in the mud after the tanks dry up." In a subsequent communication in July, 1857, the same gentleman says—"As the tanks dry up the fish congregate in the little pools till at last you find them in thousands in the moistest parts of the beds, rolling in the blue mud which is at that time about the consistence of thick gruel."
"As the moisture further evaporates the surface fish are left uncovered, and they crawl away in search of fresh pools. In one place I saw hundreds diverging in every direction, from the tank they had just abandoned to a distance of fifty or sixty yards, and still travelling onwards. In going this distance, however, they must have used muscular exertion sufficient to have taken them half a mile on level ground, for at these places all the cattle and wild animals of the neighbourhood had latterly come to drink; so that the surface was everywhere indented with footmarks in addition to the cracks in the surrounding baked mud, into which the fish tumbled in their progress. In those holes which were deep and the sides perpendicular they remained to die, and were carried off by kites and crows."
"My impression is that this migration takes place at night or before sunrise, for it was only early in the morning that I have seen them progressing, and I found that those I brought away with me in chatties appeared quiet by day, but a large proportion managed to get out of the chatties at night—some escaped altogether, others were trodden on and killed."
"One peculiarity is the large size of the vertebral column, quite disproportioned to the bulk of the fish. I particularly noticed that all in the act of migrating had their gills expanded."
Referring to the Anabas scandens, Mr. Hamilton Buchanan says, that of all the fish with which he was acquainted it is the most tenacious of life; and he has known boatmen on the Ganges to keep them for five or six days in an earthen pot without water, and daily to use what they wanted, finding them as lively and fresh as when caught.[1] Two Danish naturalists residing at Tranquebar, have contributed their authority to the fact of this fish ascending trees on the coast of Coromandel, an exploit from which it acquired its epithet of Perca scandens. Daldorf, who was a lieutenant in the Danish East India Company's service, communicated to Sir Joseph Banks, that in the year 1791 he had taken this fish from a moist cavity in the stem of a Palmyra palm, which grew near a lake. He saw it when already five feet above the ground struggling to ascend still higher;—suspending itself by its gill-covers, and bending its tail to the left, it fixed its anal fin in the cavity of the bark, and sought by expanding its body to urge its way upwards, and its march was only arrested by the hand with which he seized it.[2]
1: Fishes of the Ganges, 4to. 1822.