TROPICAL AQUARIUM FISHES 133 



practically worldwide in distribution. The two tabs seen near the lower 

 portion of the illustration are the egg-pouches of the female. These 

 develop in warm weather every two days, become detached and fall to 

 the bottom with 16 to 32 eggs which arrive at maturity in 30 days. They 

 are called Cyclops because, like the giant of mythology, they have but 

 one eye. 



Mosquito Larvae. These are often known as wrigglers and are 

 familiar to those who have looked in rain barrels. Their bodies are 

 straight and about a quarter of an inch long. They rest at an angle to 

 the surface of the water as shown in Fig. 84, with head down, and are 

 always ready to "wriggle" to the bottom at the first sign of danger. 

 From midsummer on they may be found in still water where there are 

 no fish. They are taken in the same manner as daphnia, except that 

 one has to get them with a quick sweep before they can get down into 

 the water. They can usually be seen floating together in black masses. 

 The city entomologist anywhere will give information as to where they 

 may be obtained and will be glad to have his burdens lightened by the 

 fish breeder. 



Mosquito Larvae may be termed a special food. It can only be 

 had in large quantities towards the middle and end of Summer, and is 

 only suited to the fish large enough to easily swallow it. As a food for 

 putting growth on fish an inch long or over it has no equal. The main 

 drawback to these larvse is that those not eaten quickly by the fish are 

 liable to turn to mosquitoes. This difficulty can be discounted by proper 

 management. Keep the stock of larvae in a tank covered by a sheet of 

 glass, leaving about two inches at one end not covered. Over this open 

 space place a piece of mosquito netting, drawing it up several inches 

 over the opening into a sort of inverted bag. Then draw a string 

 around top edge of tank to fasten netting down. As the mosquitoes 

 hatch they will fly upward into the netting bag, where they may be killed 

 before lifting the lid to get larvae for the fish. The larvae should be kept 

 out of the sun and as cool as possible so as to retard hatching. They will 

 stand great crowding, their only requirement being that there is room 

 for them all to get to the surface at one time, for they breathe air. This 

 is one advantage in placing larvae with fish, for, unlike daphnia, they 

 extract no oxygen from the water. By feeding them to the fish we not 

 only do well for the fish, but serve the interests of humanity by cutting 

 down the mosquito pest. In open pools goldfishes are one of the best 

 agents in keeping the neighborhood free of mosquitoes. Unfortunately 

 the mosquito larvae can live and hatch in temporary pools and in water 

 too foul for any fish to survive in. 



