Page:Handbook for Boys.djvu/131

110 Starting the Auariam

You can balance your aquarium by plenty of plants. As they grow they give off oxygen which purifies the water and

is breathed by the fish. The water need not be changed for years. The swamps and slow streams afford great numbers of plants. If you know the plants get pond weeds, Canadian water weed, ludwigia, willow moss, or tape grass. (Look in the dictionary for official names of the plants or get special books from the library.) Take some tape grass (valllisneria) to your teacher or doctor and ask Mm to show you under his microscope how the sap flows and the green coloring matter is deposited. The simplest form of vegetation is algae which grows on the slices of the tank. Lest this grow too thick, put in a few snails. Watch the snails' eggs develop in clusters. Buy ff you cannot find banded swamp snails that give birth to their young instead of laying eggs.

Any pond or stream will furnish fish that are beautiful or interesting to watch, e.g., killies, sunfish, cat-fish, carp, shiners, blacknosed dace, minnows — the mud minnow that seems to stand on his tail — darters, etc. If you get your supply from dealers, buy gold fish, of which there are several varieties, fan-tailed, comets, fringe tails and telescope eyed. Mirror carp are lively. Paradise fish are as beautiful as butterflies.

Fish Nests

Every one knows something of birds' nests. Did you ever watch sticklebacks build their barrel-like nest, or the Paradise fish Ms floating nest, and the father fish take all the care of the young? Did you ever see the newt roll her eggs in small leaves, or the caddis fly make a case of bits of stick, leaves, and sand? For a real narvel watch a pair of diving spiders weave their balloon-like nest under water and actually carry air down to fill it, so that the young may be dry though submerged.