G81 



ICHTHYOLOGY. 



Structure 



and 



Functions 

 of Pishes. 



The characters furnished by the organs of electricity 

 were for a long time overlooked, and were not even 

 permitted to constitute a generic distinction. The tor- 

 pedo was long classed with the rays ; and in many sys- 

 tems fishes with electrical organs, and such as are des- 

 titute of them, still belong to the same genus. 



Condition 

 <>1 fishes. 



Distribu- 

 tion of 

 fishes. 



Salt water 

 fishes. 



CHAP. IH. 



CONDITION OF FISHES. 



THE subjects which we propose to discuss in this 

 Chapter are rather of a miscellaneous nature, and em- 

 brace a variety of circumstances connected with the 

 natural and economical history of fishes. We shall di- 

 vide the whole into eight sections, and in these treat of 

 the distribution, migrations, education, naturalization, 

 dietetical uses, and diseases of fish ; and conclude with 

 some observations on the geological data which they 

 furnish, and the various methods which have been em- 

 ployed to preserve them in a museum. 



SECT. I. Distribution of Fishes. 



WE have already stated, that fishes naturally reside 

 in the water; but as this element is found to differ in 

 its constitution and temperature according to its situa- 

 tion, we may expect to find the finny tribes that dwell 

 in it influenced by these circumstances. At a very ear- 

 ly period, the diversity in the distribution of fishes at- 

 tracted the attention of observers. Rondeletius at last 

 attempted a division of this class of animals, from the 

 different situations in which they are found, into ma- 

 rine, fluviatile, lake, and pond fish. It will be more 

 suitable to our present purpose, to consider them as in- 

 habitants of the sea or of fresh water. 



The saltwater fishes are much more numerous 

 than those which reside in fresh water. They can- 

 not be distinguished from fresh water fishes by any 

 peculiarity of structure, or external form. They are 

 always found in the greatest numbers in tideways, 

 and on thqse banks which are formed at the junc- 

 tion of opposite currents. They in general resort to 

 a certain kind of bottom, in which we may sup. 

 pose they find a plentiful supply of food. Some arc 

 always found near rocky shores, while others prefer the 

 sandy bays. Some are found only in the open ocean, 

 and are termed pelagic ; others keep within a short dis- 

 tance of the coast, and are termed lilloral. M. Risso, 

 m the introduction to his Ic/Myologie de Nice, (8vo. 

 Paris 1810, p. xiv.) has the following interesting noti- 

 ces respecting the distribution of the fishes of the Me- 

 diterranean, which we shall give in his own words. 



Ces graneles profondeurs sont herissees de rochers 

 et ne sont frequentees que par les Squales, les Batistes, 

 les Chi meres, les Ziphias, les Gades, les Caranx 

 les Centronoles, les Lepidolcptres, les Trigles, les Cen- 

 tropomes, les Holocentres, les Bodians, les Tclragonu. 

 res, les Pomalomes. A cent 'metres des profondeur 

 en avangant vers la terre, les fond de la mer est recon- 

 vert de fange et de limon, sejour impur de Rnies, des 

 ''Opl'ies, des Cepotes, des Zees, des Pleuronectes, des 

 Oltgopodes, enfin de tous les poissons a chair molle et 

 baveuse. En continuant de s'elever' cent cinquante 

 metres de profondeur, a peu pres, la vegetation se ma- 

 mfeste: les algues, les caulinies, les ulves, les confer- 

 ves, les varecs, et les zoophytes qui tapissent ce sejour, 

 y appellent les Ophidiet, les Stromatees, les Murenes, 



les Uranoscopes, les Vives, les Scorpenes, les Periste* Condition 



diont, les Labres, les Spares, les Luijans, les Esocen, f Kishes. 



les Murenophis, &c. Viennent ensui'te les rochers du *V * ' 



rivage, ou les Syngnathcs, les Centresques, les Blen- 



nies, les Batrachoides, les Gobies, les Notopteres font 



leur demure accoutomce. Enfin les belles plaines de 



galets et de sable ou se nourrissent les Lcpado"astcres, 



les Ammodyles, les Callionymes, les Lepidopes, les Gym- 



nctras, les Osmcres, les Scombrcsoces, les Argentines, 



les Atherines, les Slolephores, les Mugil, les dunces' 



et les Serpes." 



These different depths at which fishes reside in the 

 sea, may be regulated by the presence of suitable food 

 in those places. When fishes live at a great depth, the 

 air-bag secretes more oxygen than when residing near 

 the surface ; but this is a circumstance over which the 

 fish perhaps can exercise controul ; and although the 

 pressure upon the body must increase with the depth in 

 the water, we are ignorant of the effect produced on 

 the sensations of the animal by the change. Even many 

 pelagic fish become littoral during the breeding season, 

 and the littoral fish retreat to the deep on the approach 

 of a storm. 



Thefresh-rvalcr fslies are not so important, in an Fresh wa. 

 economical point of view, as those which inhabit the ter fishes. 

 ocean. Some species frequent rivers, and seem to re- 

 quire, for the preservation of their health, a continued 

 current of water. Others live in lakes, and seem con- 

 tented to spend their days where the water is still. 

 Like salt-water fishes, they appear to prefer particular 

 altitudes; and in ascending mountains, we may ob- 

 serve that the fish in the lakes and rivers have their 

 boundaries, as well as the vegetables which cover their 

 surface. Thus Wahlenberg found, that the pike and 

 perch disappeared from the rivers of the Lapland Alps 

 along with the spruce fir, and when 3200 feet below the 

 line of perpetual snow. Ascending 200 feet higher, the 

 gwiniad and the grayling are no longer to be found in 

 the lakes. Higher up still, or about 2COO feet below 

 the line of perpetual snow, the char disappears ; and 

 beyond this boundary all fishing ceases. 



When a salt water fish is put into fresh water, its mo- 

 tions speedily become irregular, its respiration appears 

 to be affected, and unless released it soon dies. The 

 same consequences follow when a fresh water fish is 

 suddenly immersed in salt water. In what manner 

 they are influenced by the change, has never been sa- 

 tisfactorily determined. 



There are not a few fish which may be said to be am. 

 phibious, or capable of living either in fresh or salt 

 water at pleasure. Such fish, in an economical point 

 of view, are extremely valuable, as they furnish to the 

 inhabitants of this and other countries an immense sup. 

 ply of food. The salmon may be given as an instance 

 in this country, where, from one river, (Tay) 50,000 

 head of full sized fish have been obtained. To the 

 Greenlanders, their Angmarsaot, or Salmo arcticus, is 

 perhaps more valuable, as it is formed into bread, as 

 well as consumed in a fresh or salted state. 



All these fishes seem to reside chiefly in the sea. 

 There they grow and fatten; but when the time of 

 spawning approaches, they forsake the salt water, and 

 return to rivers and lakes. But this desertion of the 

 ocean is only temporary, and regulated by the circum- 

 stances connected with reproduction. The instant the 

 spawning is finished, they repair with equal rapidity 

 to the ocean, to repair their exhausted strength, and 

 fit them for obeying again the laws of their existence. 

 Some of these fishes appear to be capable of living ex. 



