ZOOLOGICAL SOCIETY BULLETIN 



1683 



AIR-BLADDER TROUBLE IN CAPTIVE 



FISHES. 



By L. L. Mowbray. 



AMONG the larger marine tropical fishes, 

 especially the groupers, kept in the Aqua- 

 rium, there are sometimes troubles arising 

 from the nature of the foods supplied. These 

 fishes in their native waters feed to a consider- 

 able extent on large crustaceans which are un- 

 obtainable as fish food for northern aquariums. 

 The lack of these bulky foods apparently affects 

 the operation of the air bladder. 



I have taken a large spiny lobster from the 

 stomach of a black grouper (Mi/cteroperca bo- 

 naci), that had been swallowed within four 

 hours after the lobster had been placed in the 

 fish trap. The stomach of the fish was so packed 

 that the outline of the lobster showed plainly. 

 The action of the gastric juices had been so rap- 

 id that the lobster, when cut out, looked as if it 

 had been boiled, and its hard shell was so soft- 

 ened that the finger could be pushed through it 

 with ease. 



A captive fish suffering from lack of bulky 

 crustacean food to keep the stomach well 

 stretched and use up the gastric juices, spends 

 much time swimming with its head out of wa- 

 ter. Occasionally it will dart downward, but 

 soon returns to the surface as if seeking air. 

 The trouble is evidently caused by contraction 

 of the walls of the stomach when hard food is 

 lacking, which in turn contracts the gullet. This 

 lias the effect of closing the air duct opening 

 from the air bladder. The air duct in such a 

 case may long have been inactive as a result of 

 the fish having been kept at an even depth, the 

 tanks being only four feet deep. Under natu- 

 ral conditions these fishes range from shallow- 

 water down to considerable depths, while in cap- 

 tivity the action of the air bladder is restricted. 



The fish gradually acquires much buoyancy 

 when living in shallow water and the tendency 

 to remain at the surface becomes greater. The 

 trouble is usually overcome by puncturing the 

 enlarged swim bladder, but this would not be 

 necessary if it could have been supplied with 

 more of its natural food. The puncture is made 

 by piercing the left wall of the body behind the 

 pectoral fin, a distance two-thirds of its length. 

 The operation is performed with a grooved nee- 

 dle. By piercing at this point the pectoral girdle 

 is cleared, and the smaller lobe of the liver be- 

 ing on the left side, its puncturing is avoided. 

 The air escapes as the needle is withdrawn, the 

 little flap of skin cut by the grooved instrument 

 falls back into place, the fish is relieved, and the 

 wound soon heals. 



This operation may again become necessary 

 unless the fish is supplied with the hard and 

 bulky food it requires. 



AQUARLST AND AQUARIAN 

 By Ida M. Mellen. 



WHAT is the correct title for a person 

 who understands the management of 

 aquaria? For some years this has been 

 a vexed question. Aquarian, Aquarium-keeper, 

 Aquarist, and other names have been given. A 

 similar difficulty accompanied the selection of a 

 word to describe a receptacle or building con- 

 taining live aquatic plants and animals, aqua- 

 vivarium and other names having been used lie- 

 fore aquarium was finally settled upon. 



The euphonius and unique name of " Aquaria] 

 Garden" was bestowed upon an aquarium opened 

 in Boston in 18(50. Professor E. S. Morse. 

 President of the Boston Society of Natural His- 

 tory, thinks it may have been suggested by Agas- 

 siz, who was greatly interested in the institu- 

 tion. The Leisure Hour of 1861 states that 

 Agassiz "may frequently be seen walking to- 

 wards the Boston Aquarial Gardens." As the 

 histories and guide-books of Boston covering 

 that period, tell very little about the opening 

 of the Aquarial Garden, it is interesting to learn 

 from Professor Morse that the exhibition con- 

 sisted of "individual aquaria round the hall, and 

 in the centre a huge tank in which seals, a shark 

 and other animals were displayed. Afterwards 

 a group of Africans, Zulus, Hottentots and 

 other negroes danced and sang on the stage." 



Such awkward words as aqua-vivarium and 

 aquarium-keeper are not likely to become popu- 

 lar. A book in our Aquarium library, published 

 sixty years ago in London, is entitled The Aqua- 

 rian Xaturalist. This is typically English. 

 From old American dictionaries we learn that 

 Aquarians were members of an heretical Chris- 

 tian sect that flourished about the middle of the 

 18th century and were so called because they 

 used only water at the Lord's Supper. Mur- 

 ray's English Dictionary, at present the stand- 

 ard dictionary in England, gives this definition 

 and also defines Aquarian as "One who keeps 

 an aquarium." It also states that the word lias 

 been used, though rarely, as an adjective, an 

 article in the Intellectual Observer for 1865 be- 

 ing entitled "Aquarian Principles." 



The word Aquarist was adopted some years 

 ago by the New York Aquarium. In perfectly 

 correct form, probably, it should be Aquariist ; 

 but the contraction is preferable. The publish- 

 ers of the Century Encyclopedia, conferring 

 witli the officers of the Aquarium on the subject 



