Page:The Book of the Aquarium and Water Cabinet.djvu/63





Points in which the Marine differs from the River Tank.—Though vessels of precisely the same construction are used for marine as well as fresh-water aquaria, yet, as the peculiar necessities of marine life demand some conditions of a special kind, I must here again briefly treat of the vessels in which marine stock may best be kept. Every variety of tank or vase referred to in the description of the fresh-water aquarium may be used in the formation of marine collections; but while vases are eminently suitable for river stock, they are not to be strongly recommended for marine, and for this important reason, that we do not generally have, as in the former case, a variety of moving forms poising in midwater, or chasing each other through every part of the tank but in the present case ground stock constitutes the main feature of attraction, and hence we require a vessel which admits of examination in every part, which a tank does and a vase does not. In a vessel containing actinia, madrepores, serpula, &c., we require to have at all times