ft 



THE 



AQUARIUM 



13 



told the writer of an interesting case 

 that came under his observation, con- 

 cerning a catfish and a goldfish. The 

 two were the sole inhabitants of a small 

 tank, and were fed upon the common 

 rice-flake food. The catfish, following 

 the usual habit of its kind, endeavored 

 to glean its food from the bottom, and 

 hence fared sparingly. This character- 

 istic of its friend seemed to cause the 

 goldfish much concern. It could be 

 seen "nosing" the catfish, evidently 

 trying to make it rise to the surface 

 where the food awaited. Finally, the 

 catfish apparently understanding the 

 good intention of its bright companion, 

 "arose to the occasion", and thereafter 

 took its food from the surface. The 

 goldfish no longer "nosed" the catfish 

 after teaching it the trick. Doubtless 

 many other instances could be cited by 

 observing aquarists, and should be com- 

 municated to The Aquarium, 



Darwin aptly says, "since animals 

 possess the same senses, it follows they 

 must possess the same fundamental 

 intuitions as man." If an animal does 

 the same thing a man would do under 

 certain circumstances, are we not justi- 

 fied in concluding that man and animal 

 are moved by the same power? 



Notes on the Air-Bladder. 



W. B. HOFFMAN, Hammond, Indiana. 



A N interesting instance of the re- 

 ^~~^- markable vitality of the life 

 principle was recorded some years ago 

 by a microscopist from an examination 

 of the bladder of a perch, and is worth 

 repeating. 



While cleaning the fish, it was ob- 

 served that the bladders were unusually 

 large, hence they were laid aside for 

 study. Under the microscope, the 

 corpuscles of the blood were found to 



be still in active movement, though the 

 fish had been caught the previous day, 

 and presumably had been dead at least 

 fifteen hours. In connection with this 

 observation, it may be added that 

 scientists have found that in animal 

 life, a considerable time may intervene 

 between apparent death and actual and 

 complete dissolution. 



The air-bladder appears to be the 

 principal factor in producing voice, at 

 least in those fishes in which that organ 

 has an opening into the aesophagus; 

 and even in those in which it is a closed 

 sac it acts as a sounding-board in aug- 

 menting the sound produced by other 

 parts. That it is not exclusively the 

 cause of vocal sounds is shown by the 

 circumstance that some fish are destitute 

 of a swimming-bladder, and yet are 

 capable of producing distinct sounds. 



Acorns as Fish Food. 



Herr R. Herold, principal superintend- 

 ent of the Ducal Fisheries of Trachen- 

 berg, gives in Allgemeine Fischerei 

 Zeitung a very interesting account of an 

 experiment in feeding fish (carp) with 

 acorn meal. In 1911 they had an un- 

 usually big crop of acorns, which gave 

 him the idea of trying them as carp 

 food. The acorns were collected in the 

 autumn of 1911, dried at a drying-mill, 

 by which they lost thirty-five per cent, 

 of weight, after being stored dry through 

 the winter, and then rough - ground 

 between stones at a windmill into a 

 medium rough kind of meal; the shells 

 were mostly cracked off lengthway by 

 the mill-stones, and not ground up, so 

 they could be sifted out, causing a 

 further 5 per cent. loss. 



Herr Herold found that it took 9cwt. 

 of coarse acorn meal, costing about 4s. 

 6d. a hundredweight, to produce lcwt. 

 of carp. The fish took it freely, and 

 made healthy growth on it. The meal 

 is described as pleasantly sweet (not at 

 all bitter or astringent, as one would 

 have imagined.) The Fishing Gazette. 



