6 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
they soon succumb. The usual method of treatment in such cases is to dip them fre- 
quently into salt water. While many other solutions, such as carbolic acid, washing 
soda, etc., are frequently used, it is quite probable that the salt water is as efficacious as 
any of them and much less liable to do harm. The labor involved, however, in treating 
a number of fish in this manner is very great, and the splashing and slopping occa- 
sioned by large fish is a further objection. 
It is also a question as to whether the injuries inflicted upon fish by the frequent 
handling of them, especially in the common knot- woven net, are not as great as the 
benefits received from the treatment. However that may be, the experiment herein 
described seems to open up a very simple and efficacious treatment of fishes so injured. 
The water in the aquarium was brought to a density of 1.006. The fish experimented 
upon were large-mouthed black bass, white bass, red-eye or rock bass, crappie, yellow 
perch, white perch, eel, sunfish, carp, goldfish, and catfish. The under lips of the black 
bass were badly torn and completely covered with fungus. There is no question in the 
minds of any who saw them and understood their condition that they would have 
speedily died in a fresh water aquarium. After a month’s sojourn in the brackish water 
they were fully restored, with a new skin grown over what were ragged festering sores. 
While in the brackish water they commenced to feed upon small minnows given them, 
whereas in the fresh water they would not feed at all. In every repetition of this 
experiment the same favorable results were obtained. 
The crappie is a timid and very deb'cate fish, easily injured by transportation. It 
is soon attacked by fungus. In every instance it has been speedily restored by the 
brackish-water treatment. All the other species mentioned were quickly cured of 
injuries or freed from fungus in the same way. 
The goldfish and carp are frequently infested by a minute infusorian parasite, the 
identity of which is not yet certain, and the catfish, sunfish, white perch, trout, and 
others, are in winter infested by a parasite, Chromatophagus parasiticus , and all of these 
have yielded to the brackish-water treatment. 
It seems assured also, from the experiments made, that any of our fresh- water 
fishes will live for an indefinite time in salt water about one-fourth the density of sea 
water; whether an artificial solution will answer as well as the sea water itself is yet 
to be determined. There is an interesting field for experiment and observation thus 
opened up in this direction. It has been found also that, to some extent at least, bene- 
ficial effects have followed the temporary transfer to brackish water of species supposed 
to live wholly in sea water. 
All of the salmon and trout may be transferred suddenly from fresh water to water 
having a density of 1.010 without inconvenience to them, and the water can then be 
brought up to the full strength in the course of two or three days. 
It should be stated that the density of the main body of water is kept at 1.020, as 
that has been found to be sufficiently saline for any species whatever, and also to be 
more generally favorable to all species. 
The aquaria have proven to be very popular, and the expressions of wonder and 
delight are universal; and many zoologists, and biologists in particular, are gratified 
that at last there is a possibility of the development of conditions affording the means 
for the study of marine as well as fresh- water forms in a living condition where access 
may be readily had to works of reference. 
Of course it is not to be assumed that the ultimate measure of success will be sud- 
