. Goldfish varieties and tropical aquarium fishes; a complete guide to aquaria and related subjects. Aquariums; Goldfish. 134 LIVING FISHFOODS usual effects of being overfed. A certain degree of care must be exercised not to place so much daphnia into the aquarium as to suf- focate the fish. Daphnia breathe the free oxygen in water the same as do fish and therefore too many will soon exhaust oxygen from water. The fish will die of suffocation sooner than the daphnia. Many beginners have lost fish in this way. A good practice is to give the fish all they can eat in about a quarter of an hour an
. Goldfish varieties and tropical aquarium fishes; a complete guide to aquaria and related subjects. Aquariums; Goldfish. 134 LIVING FISHFOODS usual effects of being overfed. A certain degree of care must be exercised not to place so much daphnia into the aquarium as to suf- focate the fish. Daphnia breathe the free oxygen in water the same as do fish and therefore too many will soon exhaust oxygen from water. The fish will die of suffocation sooner than the daphnia. Many beginners have lost fish in this way. A good practice is to give the fish all they can eat in about a quarter of an hour and still leave some few daphnia swimming 124 125 Fig. 122. Daphnia (Greatly enlarged) Fig. 123 Mosquito Larva (Greatly enlarged) Egg Raft and Individual Eggs (Greatly enlarged) Pupa Before Transforming to Mosquito (Greatly enlarged) Fig. 124. Cyclops (Greatly enlarged) Fig. 125. Cypeis (Greatly enlarged) A popular name for daphnia is "ditch ; This will give a hint as to their appearance, as they are approximately the size and shape of a flea, except that they have two rather long, branched swimming arms which are always in motion and which give the animal a sort of hopping motion through the water. Without this perpetual swimming the daphnia would sink to the bottom, as they are heavier than water and have no air bladder. A greatly magnified illustration is shown in Fig. 83. Daphnia (pronounced "daft'ney" in the vernacular) are known among fish breeders as "insects," but they are really not such, being per- fect freshwater crustaceans as much as a crayfish. The shell, though soft, contains mineral elements which are very desirable, while the flesh itself is easily digested and nutritious. This little creature is found in freshwater nearly all over the world, principally in still pools where there are no fish. For the practical purpose of catching daphnia in sufficient quantities to feed fish the collector should hunt pools in which the
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