OBSERVATIONS ON THE AQUARIA AT CENTRAL STATION. 
7 
denly attained. Much is yet to be learned regarding the requirements of all forms of 
life under artificial conditions. The temperature at one season is unfavorable for some 
species, and at another season for other species. There may be a necessity for a change 
of density of water at certain seasons for some species as well as the nearly uniform 
temperature which they find in nature by migration, and these are impossible to provide 
for under existing conditions. All of these and many other influences are matters well 
worthy of investigation in the general interests of science, to say nothing of the advance 
of knowledge necessary in the holding and handling of many of our fishes for the more 
practical purposes of propagation. 
The realization of these objects must be accomplished through the medium of years 
of investigation and patient observation and experiment, based upon a knowledge of 
past progress in this direction, and a comprehensive idea of and faith in the possibili- 
ties of fish-cultural development. All the experiences of the past, successes and fail- 
ures, point to the necessity of approximating natural conditions more closely in the 
keeping of living things in captivity. 
Some fishes are less easily kept or transported than others, principally, it is believed, 
from mental effects alone. Many are physically much more tender and more easily 
injured than others. The young of a species will endure the conditions of captivity, 
while the adult will refuse food and pine and die. 
In the future development of aquaria, and in all attempts to hold fish or other animals 
for purposes of study or propagation, all of these influences of environment must be 
considered. To ignore them is to limit the chances of success, or to invite absolute 
failure. All the advances made will be upon the lines of imitating nature more closely, 
so as to render animals measurably happy and contented by affording such conditions 
as will promote a normal and healthy physical condition and development. 
THE FRESH-WATER AQUARIA. 
There are twenty-five tanks devoted to fresh-water fishes ; they vary in capacity 
from 10 gallons to almost 300 gallons. The conditions afforded are, as a rule, unfavor- 
able, owing to the impossibility at present of having the proper amount of light for 
healthy plant growth, upon which depends the proper condition of the water as well as 
the health and happiness of the fishes. The prevalence of fungus.is very great, leading 
to the conclusion that the conditions for its development are very favorable. There are 
animal parasites, also, which at times become veritable plagues, but which, under 
natural surroundings, do not appear to exert any injurious influence on fishes. Some 
means of controlling the temperature of the water in winter would be very desirable, 
as, when it approaches the freezing point, the fish generally refuse food, and not being 
afforded the opportunity for the semi-hibernation possible to them in nature, they soon 
succumb. These matters are mentioned not as difficulties which can not be overcome, 
but rather as the unavoidable results of an enforced economy. 
One very persistent and troublesome form of parasite is described in the Report of 
the Commission for 1884, by Dr. S. Kerbert, as GJiromatophagus parasiticus. This para 
site is an infusorian which encysts itself in the skin of fishes and but few are exempt 
from its ravages. So completely will a fish become infested with them that it would be 
difficult to find a spot as big as a pin’s head free from them. Many experiments have 
been made to find means of destroying it, but, until the efficacy of confinement in 
