JujiE 1, 1865.] 



SCIENCE-GOSSIP, 



HINTS EOR iJAlUNE AQUAEIA. 



TN the early part of last year the I'ag-collectiiig 

 -^ brigade commenced its operatious ; and one of 

 <he most abundant articles of rubbish acquired by 

 its members proved to be old aquaria. This fact 

 faintly indicates two things ; viz., that fonnerly 

 aquaria were very common in London, and that from 

 some cause or other, having ceased to be of interest 

 to their owners, they have been consigned to the 

 rubbish-heap. In many cases, probably, the loss of 

 interest arose from want of success. With a view, 

 therefore, of stimulating some to renew, and others 

 to begin, the cultivation of an aquarium, we wish to 

 give a few hints for keeping one, based upon the 

 experience of several years. The word " we " is 

 used by the writer because much of the experience 

 is that of other persons ; while the tanks and bowls 

 mentioned towards the end of the paper belong to 

 a lady friend of his. 



In the first place, let the reader discard the notion 

 that aquarium-keeping is easy, but let him be con- 

 vinced that wliat is worth doing at all, is worth 

 doing well, and that the more diligently the neces- 

 sary conditions are considered, the greater is the 

 probability of success. Any attempt to cultivate 

 flowers without some knowledge of horticulture is 

 not likely to lead to a satisfactory result ; and to 

 expect to have a healthily-stocked aquarium without 

 some knowledge of the laws which govern the 

 health of its tenants, is quite as futile. 



The crabs, star-fishes, gobies, molluscs, annelides, 

 &c., of our tanks so far resemble ourselves, that 

 their health and existence depend upon the quality 

 of the medium in which they arc placed: we re- 

 quire good fresh air, while they require good fresh 

 sea-water. In an aquarium the same water is usually 

 retained as long as possible ; hence it should eon- 

 tain within it the means of supplying the requisite 

 gases. This is done by keeping up the growth of 

 a little seaweed. Each little creature is constantly 

 engaged in abstracting from the water the gaseous 

 and solid materials conducive to its existence and 

 increase, and restoring to it again those which are 

 not adapted to its nourishment. The water conse- 

 quently undergoes deterioration, and if the animals 

 ■are too numerous, they either die off or struggle on 

 ill an unhealthy state. Overstocking is a serious 

 fault; but, nevertheless, is very commonly met 

 witli among aquaria-keepers. In order to keep a 

 large stock alive, many persons introduce a large 

 supply of weed into the tank, and force its growth 

 so as to obtain as many air-bubbles as possible, as 

 it is thought that the more numerous these are, the 

 larger is the stock of other animals they will be 

 able to keep. This, we believe, is a false principle, 

 since the water only absorbs a certain proportion of 

 the ga-ses generated (chiefly oxygen), while the rest 



rises to the surface aud escapes into the air without 

 benefiting the inhabitants of the aquarium. More- 

 over, plants that are stimulated by strong light in 

 aquaria do not appear to be the healthiest. In 

 some special cases, as when water is made to flow 

 in a current through shallow vessels, plants may be 

 dispensed with, as the necessary supplies of oxygen 

 and nitrogen are absorbed by the water from the 

 atmosphere. The vegetation that grows sponta- 

 neously in the aquarium is much more likely to 

 thrive than such as has been introduced. Whether 

 the water is stationary or flo-wiug, shallow vessels 

 are preferable to deep ones, as they wUl support a 

 larger amount of life for the same area, and the 

 creatures can be more easily seen and fed. The 

 increased capability of mainiaiuing life is owing to 

 the more efBcient aeration of the water, there being 

 a smaller bulk of water to the same extent of 

 aerially-exposed surface aud of growing vegetation. 



The regulation of the temperature is another im- 

 portant point. The seas off the British coast fluc- 

 tuate between 38° and 60° P., but in tanks the 

 water should not be allowed to range beyond a 

 temperature limited by 4i° and 65°. The best de- 

 gree of heat is from 50° to 5S°, to maintain whicli 

 is one of the most difiicult, at the same time that it 

 is one of the most important things to do. Warm 

 water absorbs less air than cold ; so that a tank 

 may healthily support, saj^, twenty creatures at 

 58° F., but it would not do so at 80°, partly in con- 

 sequence of the diminished quantity of air in the 

 water. If, however, means be taken to ensure the ' 

 constant aeration of the water, the temperature 

 may be allowed to rise considerably above 58° ; but 

 there is always a large amount of risk thus incurred. 

 If the water sinks below 44", the anemones, &c., do 

 not expand as usual. Variation in temperature 

 has considerable influence on the density of sea- 

 water -when in small quantities ; so that this should 

 be taken into account when fresh water is added ; 

 the density should be kept as constant as possible 

 at 1026, an equal bulk of distilled water being equal 

 to 1000. This can be regulated by an hydrometer, 

 which ought to sink up to a line marked 1026 (or 26 

 as it is marked on some instruments). 



By especial attention to temperature, which may 

 be regulated by opening or shutting doors and 

 windows, burning gas, partially covering the tanks 

 with damp cloths, and adopting other means, so as 

 to keep the thermometer within the limits we have 

 mentioned, at the same time taking care that the 

 temperature does not rise or fall rapidlj^, most of the 

 denizens of the aquarium may be kept in a flourish- 

 ing condition for prolonged periods. 



The limited space at our disposal forbids our saj'- 

 iug more at present, but we may briefly sum up 

 thus. Do not overstock; keep Ihc aquarium in a 

 spot where the light docs not exceed in intensity the 



