The Aquarium and its Management. 
263 
non-successful aquarians. For instance, the water has never once 
been pea-soupy, or even cloudy, or otherwise than as brilliant as all 
that we have in our mind’s eye when talking of the “ crystal 
spring” and the beverage of Castaly. There have been deaths in it—deaths 
by compulsion, the result solely of experiments made with a view to test the 
extreme capabilities of the system ; but we have managed to keep gold¬ 
fishes healthy and happy therein, during a period of more than twelve years. 
Furthermore, to keep this tank in order is a matter of such small trouble that 
it may be literally said to take care of itself. Ordinary dusting and occasional 
cleansing of the exterior are, of course, necessary, and for the interior there 
are two operations only that are needful. The fishes are fed with rice boiled 
in water, or with bread crumbs. Undoubtedly bread is as good a food as they 
can have, and as it is always handy, it is a great advantage to be able thus 
simply to perform a duty which is generally too much neglected, for there are 
still to be found some benighted people who think that gold-fishes can live 
on the invisible tenants of the tank, and get fat, as it were, upon nothing. 
The other operation is the occasional cleansing of the front plate inside. 
This is accomplished by means of a piece of sponge, attached, by means of 
twine, to the end of a stick, and the stick is thrust behind the tank, so as to 
be always handy for the purpose. This cleansing of the front plate is per¬ 
formed about once a fortnight during summer, and not more than once in 
three months during winter; in fact, it might be left undone from November 
to March, and the view would be unimpaired by even the slightest film of 
conferva ; but from March to October the growth is sufficiently rapid to 
produce a perceptible green tinge on the glass in eight or ten days, and this 
is easily removed by the sponge. In cases of long neglect we find the most 
effectual mode of cleansing to be with a cloth on which a little silver sand is 
sprinkled ; this, drawn over the glass with the sand, brings away the crust at 
once, and if carefully done, appears not to cause any serious scratching of the 
glass, though if the glass were of poor quality, perhaps it might. 
The reader has, of course, taken note of the omission from this history of 
all mention of the introduction of plants to the tank. We have never intro¬ 
duced a plant of any kind, yet the rocky wall is richly coloured with micro¬ 
scopic forms of vegetation in beautiful green, bronze and russet patches, and 
if the glass ends are left untouched, they in time become quite opaque with a 
dense coating of olive-coloured vegetation. This is one of the grand features 
of the natural system. We may introduce a thousand plants, Anacharis, Vallis- 
