Our own fish‐houses at the Zoological Gardens were first opened in 1853, while those of the French Acclimatisation Society in the Bois de Boulogne were inaugurated in 1861. Now almost every capital possesses one on a grand scale. That at Naples is especially noted. At the Continental fishery exhibitions, held at Amsterdam, The Hague, Boulogne, Havre, Arcachon, &c., temporary aquaria always form part of the attractions. The dimensions of the great aquarium at Brighton are as follows: Its area is 716 feet by 100 feet, the great tank alone containing 110,000 gallons of water, and having a plate glass front 130 feet long, through which the habits of very large fish may be studied. The rock‐work of the tanks is artificial, and admirably adapted to give shelter to the fish and crustaceans which disport in them. The management of a large aquarium involves constant care, and it is quite possible to kill its inhabitants by too frequently changing the water—by over‐kindness, in fact. The aquaria at Brighton and the Crystal Palace are very differently constructed and managed. At the former there is no actual circulation of water from one tank to another, but it can, if necessary, be renewed from the sea; the mass of the water in the reserve tanks is small as compared with that in the show tanks, and aëration is effected by pumping air into the tanks through tubes of large diameter. At the Crystal Palace aquarium a constant circulation is maintained from one tank to another; the bulk of water in the reservoir is five times as much as that in the show tanks, while aëration is accomplished by carrying a main over their entire length, from which, under pressure, a small stream of water pours from a tap into each, breaking the surface of the water, and carrying down to the bottom of the tanks and distributing over the body of their contents myriads of minute bubbles of air, which present an enormous oxydising surface to the water, rendering it bright and sparkling. It does not answer to change the water too constantly, while some obnoxious specimens, like the flat‐fish, foul it greatly, the remedy for which is found in putting animals in who in the economy of Nature act as scavengers. Various small animals have to be supplied as food for the larger ones. “As the animal life and vegetable life mutually support each other, the kind of material necessary for maintaining the ‘compensating system’ must be watchfully supplied. Mr. W. R. Hughes, of Birmingham, recommends the growth of sea lettuce (_Alva latissima_) in tanks, as suitable both for oxygenating the water and for food for the fishes; the stock plants being introduced in the autumn months, when they are loaded with spores.” The writer of the article in the “Encyclopædia Britannica,” from which most of the above is taken, ventures to hope that the aquarium may become useful in a practical sense, and may determine many questions in regard to fish life and growth concerning which we are ignorant to‐day.