Photograph ing Fish 221 



picture, but is also an aid from a scientific stand- 

 point in determining the species. 



The exposure necessary is entirely according to 

 whether your specimen is of a quiet turn of mind 

 or not. Usually from to ^ of a second will be 

 found fast enough, but occasionally greater speed 

 is necessary, and sometimes a specimen will remain 

 still enough for a sufficient length of time to allow 

 of a time exposure, but it is best never to depend 

 upon this. 



It is always a good plan to make several expos- 

 ures on the same specimen. This decreases the 

 chances of failure, and should each negative prove 

 good the change of the position of your subject 

 will make each one of them valuable ; while if but 

 one exposure is made, and that should turn out 

 poorly, you will have had all your trouble and 

 used your time and patience for nothing. More- 

 over, many fish change their coloring and markings 

 very materially, at times often suddenly, and ap- 

 parently without cause or reason. It is sometimes 

 done, however, as a means of protection by con- 

 forming more nearly to the colors of their sur- 

 roundings, and, when possible, pictures showing 

 the various phases should be made. The fish of 

 the tropical waters are the ones that show the 

 most pronounced changes, and with some these 

 changes are so decided as to completely alter the 

 appearance of the specimen. 





