274 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
in tlie abundance of fish ; for both the sardine and frozen-herring in- 
dustries have assumed important proportions, and men find remunera- 
tive employment in connection with them, thus avoiding the exposures, 
dangers, and hardships to which they were formerly subjected when 
fishing for haddock. At present only two firms engage at all in smok- 
ing haddock; one of these preparing only sufficient quantities to supply 
the local trade, while the other smokes small quantities for shipment 
to Portland. Those best informed estimate that less than 25 tons of 
haddock were smoked at Eastport during the season of 1885-’86, the 
few sent out of the city being consigned to Portland dealers. 
57. — TSI53 AQUARIUM. 
A BRIEF EXPOSITION OF ITS PRINCIPLED 
AN® MANAGEMENT. 
By WILLIAM P. SEAL. 
The history of the discovery and application of the principles of the 
aquarium is so well known that it is not worth while to repeat it here. 
Many books have been written upon the subject, all of them in a spirit 
of glowing enthusiasm, but generally lacking information upon the most 
essential points, and often grossly misleading as to elementary prin- 
ciples. 
A well-managed aquarium requires but little attention, and is a de- 
light to all lovers of nature. It is a living ever-changing picture. On 
the other hand, under improper conditions an aquarium is a trouble, 
and is not calculated to give pleasure to the refined and cultivated. 
Certain conditions are absolutely essential to the successful working of 
the aquarium. The most important of these is absolute purity in the 
tank or vessel used, and an abundance of light. When these primary 
conditions are not obtainable, discouragement and eventual failure are 
certain. The dealer in aquaria, in his eagerness to make a sale, may 
advise differently. There is probably no business which has been more 
abused by false statements and a withholding of the truth, or from ig- 
norance of the subject, and none is more in need of plain truth telling 
to elevate it to the position it should occupy in affording a means of 
popular amusement and instruction. 
When once properly understood the aquarium, with its varied and 
interesting forms of life— animal and vegetable — will become as com- 
mon a feature of household adornment as are birds and flowers. 
The newly awakened general interest in biological research, or, in 
plainer words, the study of life, has opened up an extended field for the 
aquarium as the medium for observation of the habits, developments, 
and metamorphoses of animals and plants inhabiting the water. As 
an adjunct to the microscope for the amateur or for the specialist, it is 
an absolute necessity. For the young as a means of encouraging habits 
of observation and feelings of humanity, as something to give a sense 
