40 



Aquatic JLitt 



Breeding Habits of 

 The Burmese Eel 



This eel (Amphipurus euchia), which 

 is brought at times to us from China, is 

 well known to many of us, and for eight 

 years I have had three of them in a rather 

 large tank. On the ;th of January I 

 noticed that some eggs had just been laid, 

 giving me the opportunity of studying 

 the behavior of the adult fish towards 

 the eggs. 



Many of you know how the Paradise 

 Fish (Macropodus) breeds, and have 

 watched the construction of the nest and 

 the method of depositing the eggs. The 

 fish makes a nest of air-bells by inhaling 

 air from the surface, holding it in the 

 mouth for a short time, and then letting 

 it escape mixed with saliva. A mass of 

 coherent air-bells, two to three inches in 

 circumference, is thus formed, and the 

 eggs which have been laid are gathered 

 by the male fish in his mouth and placed 

 amongst the air bubbles. He watches 

 over the eggs until hatched, and the 

 young until old enough to take care of 

 themselves. 



The Burmese eel acts in a very similar 

 manner. Always the one eel gathers the 

 eggs and places them in the air-bubble 

 nest, watching them unremittingly until 

 hatched. The eggs are fairly heavy and 

 readily sink from the nest when the tank 

 is tapped or the water disturbed ; but the 

 fish replaces them immediately. I have 

 seen the eel gather as many as eight eggs 

 in his mouth at once, and then put them 

 back in the nest. He pokes his head right 

 through the nest and endeavors to place 

 the eggs on top of the mass of bubbles. 



In about eight days the young are 

 plainly visible, wriggling about in the 

 sgg. The eggs, being on top of the nest, 

 and in some cases quite half an inch 

 above water-level, are fairly dry, and the 



embryo eels become very active when the 

 eggs are moistened by sprinkling with 

 water. 



The eggs hatch in twelve days, and the 

 young remain in the nest for quite a 

 week. A couple of weeks after the eggs 

 were laid I found one of the adults at 

 the bottom of the tank. Perhaps it had 

 been trying to get at the young and had 

 paid the penalty. — H. E. Finckh, in 

 The Australian Naturalist. 



The Name "Water-flea" 



The origin of "water-flea" as a com- 

 mon name for Daphnia, which are not 

 insects, is explained in the following ex- 

 cerpt from the chapter on the Cladocera ; 

 by Birge, in Fresh Water Biology : 



"When men began to study nature by 

 the aid of the microscope in the seventh 

 century the "insects" were among the 

 first objects to be examined. In 1669 

 the Dutch physician, Swammerdam, de- 

 scribed in his history of insects the 

 'pulex aquaticus arborescens' — the water- 

 flea with branching arms. This was one 

 of the Cladocera, still called Daphnia 

 pul ex, the commonest species in shallow 

 pools. These creatures he described and 

 figured, giving an account of their struc- 

 ture and habits and speaking of their 

 sudden appearance in enormous numbers, 

 and their equally sudden disappearance. 



For nearly a century little was added 

 to the knowledge of the group. In 1755, 

 the German, Schaeffer, gave the first 

 really good account of their structure. 

 In 1785, O. F. Mueller, the Danish nat- 

 uralist, issued the first general systematic 

 work upon Entomostraca. This described 

 many of the species as we now know 

 them, and gave a firm scientific basis for 

 further knowledge of the Cladocera. In 

 the rapid advance of science during the 

 latter half of the nineteenth century the 

 systematic work of the group was sub- 



