GENERAL MANAGEMENT.
Feeding should be performed twice or thrice a week, and will be as amusing to the observer as gratifying to the fishes. Bread is not so objectionable as many have stated. Carp, bleak, and minnows eat it greedily, and soon grow tame if regularly fed with it. Most small fishes take insects, such as flies, spiders, ants, and soft larva, greedily; but the large fish disdain such diet. Small red worms, and white of egg, are good general foods, and seem highly beneficial. When feeding, see that the carp get enough, for they are slow fish, and get robbed wholesale by their more lively neighbours. Food not eaten will decay, unless speedily removed, hence care must be exercised on this head.
Confervæ.—When the tank has been established a few weeks, the inner sides of the glass will show signs of a green tinge, of a slimy nature. This is owing to the growth upon it of minute forms of vegetation. If this is allowed to go on unchecked, the glass will in time become opaque, and the view of the interior will be lost. Hence it must either be kept down in growth or occasionally removed.
Uses of Mollusks.—It is to prevent this rapid growth that water-snails are registered among the tenants of right, for these creatures subsist on vegetable matter only, and if a goodly number be thrown in, they will be found perpetually at work, eating the green growth from the sides, and thus constantly preserving an open prospect.
Objections to Mollusks.—In a highly ornamental tank, water-snails may be thought objectionable, as interfering somewhat with the beauty of the scene. I know the ardent naturalist will cry out against this remark, and ask me if I can find a prettier object than a Planorbis corneus, coiled round like a horn of plenty; or a full-grown Paludina with its globular hybernaculum richly bronzed and mottled. I tell my friend that I love the pretty creatures as much as he does, yet, as I write for everybody who wishes to keep an aquarium, I feel bound to consider how it is to be managed without them, if their absence is desired. I confess too, that I do object to their appearance in some cases myself, as I do also to beetles, and all other insects in a tank fitted up for the adornment of a drawing-room, however necessary they may be in the tank of a student.
In the first place, Paludinæ and Planorbis are the only kinds to be trusted in a general collection of plants, and the last is most trustworthy of any. Lymnea are all fond of substantial dishes, and eat as much vallisneria as they do of the mucuous growth. A dozen of these gentry will most effectually check the vegetation of the tank, by eating holes in the handsomest leaves of the Stratoides, and biting into the very heart of the Vallisneria. Starwort, too, they are very fond of, and soon clear the bottom of every fragment. Yet, the Lymnea are admirable cleaners, the pity is, that they will not see what is required of them, and do that only.
Again, the univalve mollusks do not keep the sides so clean, but that an occasional cleansing of another kind is sometimes necessary, and if the aquarian is not disposed to keep an army of quite semi-efficient scavengers, the remedy will be found in an occasional cleansing of the sides, by means of a sponge attached to a stick, which must be plied over the whole surface, and occasionally taken out and washed in clean water, to remove the green scum, that it soon gets covered with.
Use of Confervoid Growths.—But I should object to any frenzy about cleansing tanks. As I said at starting, they should be self-supporting, and if Planorbis or Paludinæ are used in the proportion of about four of each to every gallon of water, a good view will always be preserved with the use, now and then, of the sponge alone.