150 Embryology and Growth of Fishes 



(Cyprinus carpio) and the Japanese goldfish (Carassius auratus) 

 have been naturalized in almost all temperate and tropical river 

 basins. Within the limits of clear, cold waters most of the 

 salmon and trout are readily transplanted. But some similar 



FIG. 116. Snake-headed China-fish, Ophiocephalus barca. India. (After Day.) 



fishes (as the grayling) are very sensitive to the least change in 

 conditions. Most of the catfish (Siluridcs) will thrive in almost 

 any fresh waters except those which are very cold. 



Transportation of Fishes. The eggs of species of salmon, placed 

 in ice to retard their development, have been successfully trans- 

 planted to great distances. The quinnat-salmon has been thus 

 transferred from California to Australia. It has been found 

 possible to stock rivers and lakes with desirable species, or to 

 restock those in which the fish-supply has been partly destroyed, 

 through the means of artificially impregnated eggs. 



The method still followed is said to be the discovery of J. L. 

 Jacobi of Westphalia (about 1760). This process permits the 

 saving of nearly all the eggs produced by the individuals taken. 

 In a condition of nature very many of these eggs would be 

 left unfertilized, or be destroyed by other animals. Fishes are 

 readily kept in captivity in properly constructed aquaria. Un- 

 less injured in capture or transportation, there are few species 

 outside the deep seas' which cannot adapt themselves to life in 

 a well-constructed aquarium. 



Reproduction of Lost Parts. Fishes have little power to re- 

 produce lost parts. Only the tips of fleshy structures are, 

 thus restored after injury. Sometimes a fish in which the tail 

 has been bitten off will survive the injury. The wound will 

 heal, leaving the animal with a truncate body, fin-rays some- 

 times arising from the scars. 



