NATUEAL SCIENCE NEWS. 



bladders. Its leaves are much 

 coarser and stiffer than those of 

 Utricularia and stand out on all 

 sides of the stems, hardly collaps- 

 ing when they are removed from 

 the water. The flowers are incon- 

 spicuous, and are borne singly in 

 the axils of the leaves. Such 

 plants as these furnish shelter for 

 fish, and supply food for them in 

 the minute animals and plants 

 which swarm among their branches. 



One of the oddities of plant life 

 which is interesting for an aquar- 

 ium is "duckweed" (Jemna). It is 

 often seen absolutely covering the 

 surface of small ponds, giving them 

 a bright, green color. The plant 

 has no stem or leaves, but consists 

 simply of an oval disc from which 

 may grow two or three others as 

 buds. They float flat on the wa- 

 ter, and from the underside there 

 hang down several slender, 

 straight, unbranched roots. These 

 furnish a refuge for many minute 

 animals and plants. The flowers 

 of duckweed are very minute and 

 rise from the edge of the disc. 



Having our aquarium supplied 

 with plants we must decide what 

 and how many animals to put in 

 it. This must depend somewhat 

 on the purpose for which the 

 aquarium is prepared. If for sci- 

 entific study we want, of course, 

 those animals which we propose 

 to study. If the purpose is sim- 

 ply pleasure, nothing is more sat- 

 isfactory than fish. In choosing 

 these one must be guided by his 

 own preference and by his sur- 

 roundings. To my own mind 

 some of our native fish are much 

 more interesting than gold fish. 

 The little sticklebacks make very 

 attractive inhabitants, but prob- 

 ably all could not procure them. 

 Perhaps the most satisfactory ones 

 will be some of the small fish call- 

 ed sunfish, roach, pumpkinseeds, 

 and by various other names. 

 These are beautifully colored; they 

 are easily kept and very active. 

 There is one drawback to their use 

 — they are very pugnacious, and 

 are likely to attack any other fish 

 put in with them. A single sun- 

 fish has been known to eat a hun- 

 dred trout fry in one day. Of 

 course this was under exceptional 

 circumstances, but it serves to 

 show their character. If you put 

 other fish in with your sunfish, be 

 sure that they are able to take 

 care of themselves. 



One must be very careful not to 

 over-stock his aquarium. For one 

 16 by 30 inches, two or three sun- 

 fish three inches long will be plen- 

 ty. If more are put in, they are 



likely to die, unless the water is 

 frequently changed. If one lives 

 where they abound, a very small 

 crayfish or two will be an interest- 

 ing addition to your aquarium. I 

 have kept one for more than a 

 year. A crayfish will burrow in 

 the sand under the stones, and will 

 not always be willing to show it- 

 self to trie public; but when it 

 does appear its actions are inter- 

 esting. If you are not familiar 

 with its habits, you will be sur- 

 prised some day to find the empty 

 shell lying on the bottom, looking 

 as if its owner had been killed. 

 You will doubtless find the latter 

 under some stone waiting for his 

 new shell to harden. He has sim- 

 ply been moulting. The most 

 amusing occupants of my aquar- 

 ium were a couple of tiny snap- 

 ping turtles, with shells not much 

 more than an inch long. Their 

 queer doings were described in 

 this paper some years ago. They 

 would probably not molest fair- 

 sized sunfish, but small or weak 

 fish would not be safe with them. 

 Of course, if turtles form a part 

 of the "happy family," there 

 should be a bit of rock projecting 

 above the surface, on which they 

 may rest. 



To manage an aquarium suc- 

 cessfully, one must get the right 

 proportion between the plant and 

 the animal life. This can be de- 

 termined only by experiment. If 

 the fish act as il in want of air, 

 gasping at the surface of the water 

 or turning on their backs, it is cer- 

 tain that you have too many of 

 them in the tank. If, on the other 

 hand, the plants sec m likely to fill 

 up the tank, grov.ing too vigor- 

 ously, more animals of some sort 

 should be added. Pond snails are 

 excellent scavengers, and are said 

 to be especially useful in cleaning 

 off the scum which is sometimes 

 caused by the growth of minute 

 plants on the glass. One object- 

 ion which I have to snails is that 

 they are extremely vigorous, and, 

 if numerous, will c at off the green 

 parts of the water plants. They 

 multiply very rapidly, and one 

 soon finds the glass coated with a 

 slimy mass of eggs, giving place 

 in a few days to young snails which 

 eat every plant within reach. If 

 you use snails as scavengers, do 

 not let them g ^t too numerous. 

 Of course, in addition to the ani- 

 mals put intentionally into the 

 aquarium, one will find many 

 small ones introduced with the 

 plants or in the water. 



The aquarium should be set 

 where it will receive good light, 



but not stand long in the direct 

 sunlight. The water will not 

 need changing unless you have too 

 many animals or not enough plants 

 in the tank. The reason is this: 

 Of course we know that fish, like 

 other aquatic animals, breathe the 

 air contained in the water, using 

 the oxygen and giving back into 

 the water carbon dioxide. The 

 reason why the fish sometimes 

 come to the surface and appear 

 distressed is, that their supply of 

 oxygen has failed, and they are 

 unable to breathe. If we add 

 fresh water we renew the supply. 

 Now the advantage of having 

 plants in the water is this: Green 

 plants use up as food carbon diox- 

 ide, when acted on by sunlight. 

 They combine this with water, 

 and from these substances manu- 

 facture starch, giving off the extra 

 oxygen into the water. One can 

 prove this for himself by putting 

 some water plant in a jar and 

 placing over it an inverted funnel 

 so that the whole is submerged. 

 Then fill a glass tube (closed at 

 one end ) with water; place the 

 ihumb over the open end and, in- 

 verting it, slip it down over the 

 neck of the funnel in such a way 

 that it remains full of water. If 

 the whole jar be placed in the sun- 

 light, bubbles of gas will begin to 

 rise rapidly into the tube, and fin- 

 ally it will be filled with gas. By 

 putting a glowing match into this 

 we can prove that it is oxygen, 

 the match blazing up at once. It 

 is evident, then, that the growth 

 of plants in the water continually 

 replenishes the supply of oxygen 

 for the animals, at the same time 

 using up the carbon dioxide. If 

 the proper balance is preserved 

 between animals and plants, the 

 water will remain clear and both 

 will thrive. Of course the loss of 

 water by evaporation should be 

 made good. 



As to the question of feeding 

 fish, opinions may differ. With 

 plenty of plants growing in the 

 aquarium, fish ought to be able to 

 find enough food for themselves. 

 If it is necessary to feed them at 

 all, a very small amount of bread 

 or cake crumbs will suffice, or 

 better still a few scrapings of raw 

 meat. Care should be taken to 

 supply very little food, for if any 

 is left uneaten it will foul the 

 water. Ordinarily it will hardly 

 be necessary to feed at all unless 

 the fish seem especially hungry. 

 The other smaller inhabitants of 

 the aquarium will be able " to take 

 care of themselves. — The Cultivat- 

 or and Country Gentleman. 



