Even after half an hour there was not the 
The strength 
of the solution was gradually increased until 
least sign of any ill effects. 
10 drops of formaldehyde to a quart of 
water produced an unnatural quietness in an- 
other fish after 15 minutes. When it was re- 
moved to fresh water we thought it was all 
up with the little fellows, no respiration, no 
movements of the fins; but, presently, a 
gasp, a wriggle, and he was a live fish once 
more. The same result occurred with an- 
other fish in 20 drops to a quart for one 
minute. Our hint of a remedy had thus 
become a hope. 
We subjected all of our remaining fish, 
eight in number, to a bath in a solution of 
five drops of formaldehyde to a quart of 
water for 15 minutes on two consecutive 
days, disinfecting the aquarium and every- 
thing about it each time with a solution of a 
teaspoonful of formaldehyde in a quart of 
water. Microscopic examination revealed 
live flukes still. We increased the strength 
to 10 drops the third day. 
could be found. 
No more flukes 
To make sure that any 
adults lurking under the seales might be 
destroyed and to kill a possible new crop, 
we repeated this bath twice more, three 
days apart, disinfecting everything each 
time. Since then frequent and thorough 
searches have failed to show the parasite. 
It 
weaker fish were affected more seriously by 
was of interest to observe that the 
the formaldehyde than the stronger ones 
and that, as they recovered, they were af- 
fected less and less by the drug. 
Three of the eight fish to receive the 
first treatment died before the treatment 
was completed, but the five survivors are 
now all bright and happy, with fins wide- 
spread, respiration normal, and appetites 
and digestion of the best; and it has been 
three weeks since they had their last treat- 
ment. One of the old ones, which we have 
had four years, has lost patches of scales, 
but this is the only remaining sign of the 
dreadful ordeal through which they have 
passed. We firmly believe that, had we 
47 
used the formaldehyde solution at the be- 
ginning of the trouble, the majority, if not 
all, of our pets would have been saved. 
Having no more patients for further ex- 
periments, we are unable to determine the 
proper strength of the solution and length 
of time for the bath to obtain the best re- 
sults, and would suggest that the aquarist 
meeting with this, or any other parasitic 
horror, try a weaker solution and greater 
length of time for the bath. It may be 
that such treatment would be as effective in 
destroying the parasites and less injurious to 
the fish. The individual can never know 
what the rest of the world is, or has been 
doing. Others may have used the same 
remedy, which has been original with us, 
but, as we have not found this treatment or 
any other practical one mentioned in any of 
the subject, 
prompted to give the readers of this maga- 
our literature on we are 
zine the benefit of our experience in the 
hope that, if the facts given are not gener- 
ally known, others with better facilities 
for experimenting than we have at hand 
may carry the tests to a more definite end 
and give the results to lovers of aquatic life. 
While formaldehyde is extremely fatal to 
lower orders of life, it is not excessively 
poisonous to the higher forms. It is, how- 
ever, an irritant to the mucous membranes 
and should, therefore, be used with great 
caution. 
The aquarist will find that little instru- 
ment, the microscope (without which sur- 
gery would still be butchery and the Pana- 
ma Canal merely a hope of the nations), a 
valuable addition to his paraphernalia. It 
need not be an expensive one; even 100 or 
150 diameters will reveal the existence of 
dangerous parasites, and afford many pleas- 
ant hours studying the many forms of harm- 
less animaleule which inhabit all aquariums. 
Tue distribution of freshwater fishes 
offers some of the most perplexing problems 
of animal distribution known to zoologists. 
This is true, not only of families, but even 
of species, whose peculiar range is often un- 
accountable. 
