1284 



ZOOLOGICAL SOCIETY BULLETIN 



exteiisivL-ly studied in all other domestic ani- 

 mals. The deeomposition of protein in the or- 

 ganism is followed by studying the nitrogenous 

 content of the excreta, while the destruction of 

 carbohydrates and fats, which on combustion 

 yield water and carbonic acid, is appraised 

 through knowledge of the resjjiratory exchange 

 of gases. It is very important for the fish cul- 

 turist to understand the phenomena which ini- 

 derlie the utilization of foods in the body. The 

 utilization of food in the higher animal organ- 

 isms has been exhaustively studied by students 

 of dietetics. This jiroblem is equallv vital with 

 regard to fishes. 



It was my privilege to be entrusted by the. 

 L'nited States Bureau of Fisheries with the 

 study of the nutrition of fish. The experiments 

 are partially c(mducted in the New York Aqua- 

 rium. The laboratory facilities there for scien- 

 tific research in this line are unfortunately very 

 inadequate, but I wish to acknowledge my grat- 

 ification to the Director and employees of the 

 Aquarium who have helped me greatly in the 

 work. 



The procedure which I follow in my investi- 

 gation is essentially the same as that employed 

 in nutrition researches on man or other domestic 

 animals. The different conditions of existence 

 of my experimental animals necessitated, of 

 course, different methods. This much may be 

 stated: by analyzing the food of every feeding 

 and the foeeal and urinary excreta following 

 each feeding, a careful comparison of intake 

 and outgo is made possible. One is thus ena- 

 bled to draw up a balance sheet which, at a 

 glance enables one to determine whether or not 

 a particular food, or food prepared in a par- 

 ticular way. is well utilized by the fish. The 

 utilization of each constituent part of the food 

 can thus be expressed in pereents and standard 

 conditions thus mav be worked out, a deviation 

 from which would unmistakably indicate the 

 relative efficiency of the organism or the rela- 

 tive nutritional value of the foods. Thus the 

 brook trout does not utilize cooked food as well 

 as uncooked, while a fast even of short duration 

 im))airs seriously its capacity for utilizing food, 

 especially fats. From the balance sheet of in- 

 take and output it is futhermore possible to 

 discover exactly how much of each element the 

 organism has added to or lost from its bodily 

 reserves. We can tell whether it grows at a 

 normal rate, putting on flesh and fat and can 

 regulate the conditions to obtain the best results. 



Domestication invariably means the substitu- 

 tion of artificial contrivances for natural condi- 

 tions. Science, determining the facts with the 



aid of objective and careful methods, furnishes 

 the fundamental princijiles in the adjustment 

 of means to particular ends. The two must 

 progress together. 



A HAPPY FAMILY OF FISHES. 



ONE of the lessons the Aquarium keepers 

 have to learn is not to put different kind? 

 of fishes in the same tank without consid- 

 ering the compatibilities. Fishes commit mur- 

 der and indulge in cannibalism with alarming 

 frequency. Their morals, like those of some 

 other vertebrates, are no better than they should 

 be. Fishes of the same species when kept in 

 Aquarium tanks must usually be of about the 

 same size or the very small ones may turn up 

 missing. 



Fish like to eat fish .and generally do so when 

 they get the chance. 



When fishes of the same size fight among 

 themselves it is necessary to sort out the chief 

 aggressors and locate them elsewhere. 



Experience teaches the kee))ers what combi- 

 nations can be made without losses of specimens. 



The Happy Family of fishes shown in the 

 accompanying frontispiece has been slowly 

 growing since the jihoto was made several 

 montlis ago. 



The tank now contains the following species 

 which manage to get on together without seri- 

 ous quarrel : 



Red Hind (Epiiuphiliis i/iittatiifi). Rock 

 Hind, (Epinephehis adsct'iicionis) . Black 

 Grouper (Mi/cfornperca boiiari). Green Moray, 

 ( Li/coiidonfis fintehris). Spade-fish, {Chaetodip- 

 tcrus faber). Pork fish (Ani.soircmus virf/ini- 

 <us). Dog Snapper (Xeomapni.i jocu), Spot 

 Snap]5er (Neomacnis .ii/narjri.i). Gray Snapper 

 (Neomaenis griseits), .Schoolmaster (Neomaeiiis 

 apndiix). Mutton fish (\^cnmai-ni.': aiialis), Cre— 

 valle (Caran.f Jiippos), Yellow Mackerel (Car- 

 an.r cri/sos). Neverbitc (C(ir(iii.v rubra). Blue 

 striped Grunt (Haemiilon xfriatus). Golden 

 Grunt (Hapmiiloii mrlaniirum). Red Hogfish 

 {Lachnolahnus ma.rinms). .Spanish hogfisli 

 (Harpc riifa). Blue Angelfish {.Ingctichthi/s 

 rsabeUifn). Black Angelfish (Pomncniithiis ar- 

 ena tii.t) . French Angelfish (Piimnraiithiix parti), 

 .Squirrclfish {Holnceiitris adsrriirioiiis) . Queen 

 Triggerfish (Ballstes I'ciidn). Common Trigger- 

 fish (Baliitf'.i rarolinrnsi.i). Blue Parrotfish 

 (ScaniK cocnih'iix). Chub (Ki/pJin.iiis scclafri.r). 



C. H. T. 



