OBSERVATIONS ON INSTANTANEOUS 
CHANGES IN COLOR AMONG 
TOPICAL FISHES: 
By CHARLES He TOWNSEND: 
EARLY all the tropical fishes on exhibition in the New 
York Aquarium have the capacity of instantaneous changes 
in color according to their moods or artificial excitements, and 
their many phases of coloration and markings have become more 
noticeable under recently improved conditions of management. 
Since July, 1908, sea fishes in the Aquarium have been kept 
in pure sea water supplied from a reservoir containing 100,000 
gallons, the use of the brackish and impure water of the harbor 
having been abandoned, except in certain very large pools. The 
temperature and salinity of the water approximate those to which 
the fishes are accustomed in nature. 
The glass-fronted exhibition tanks, some of which are eight 
feet long, are lined with artificial rockwork, and have the bot- 
toms covered with sand or gravel, all of which assists in making 
the conditions of captivity decidedly favorable. The fishes spend 
much time resting among the rock crevices or on the white sand 
below. 
The various species of fishes from the Bermuda Islands are 
now maintained in better condition than ever before, and most 
of them have adapted themselves to captivity, feeding, playing 
or fighting in apparently natural ways. 
It is well known that sea fishes habitually frequenting green or 
yellow seaweed acquire and maintain the general color tone of 
their habitat, and that trout from dark water are dark colored, 
while those inhabiting waters where there is sandy or gravelly 
bottom are light colored. 
Such conditions have long been appreciated at the New York 
Aquarium, where fishes kept in tanks lined with white tiles, ha- 
bitually wear their lighter colors, only an occasional blind fish 
remaining unchanged. The pale, colorless blind fishes of the 
Mammoth Cave gradually become darker when exposed to light 
in the Aquarium. These fishes, although with eyes practically 
useless, are still able to distinguish light from darkness. A speci- 
men from Mammoth Cave which has lived in the New York 
Aquarium three years has gradually become quite dark. 
