Make your own choice. Personally, I have an aversion to most goldfish bowls because it annoys me to see the fish kept in small containers which are little more than prisons. If you buy a bowl, buy a big one, 10 or 12 inches in diameter, and do not overcrowd it. The keystone and the flat-sided types illustrated here are the most efficient designs you will find. If you choose a small container, do stock it accordingly, perhaps with only one fish.

Flat-sided, plate-glass aquariums are the easiest to keep clean, give you the best show, and are inexpensive, particularly if you can find one second-hand. Being fragile, they do not travel as safely as other household effects when a family moves. For this reason, aquariums show up frequently as used, but still usable, merchandise in second-hand stores, junk shops, and at auctions of household goods.

However, new aquariums of standard shapes and sizes are not expensive. Even aquariums which are custom built for some special scheme of decoration are reasonable enough.

An aquarium out of use for a long time will often leak when first filled again. If seepage at the seams is slight, throw a handful of mud into the water and stir it up. Then let it set overnight. If this fails, empty the aquarium and apply stiff, clean clay as caulking around the inside seams. Finally, if the aquarium continues to leak, empty it, wash it thoroughly, dry it, and then cover all cracks along the inside seams with a good grade of waterproof varnish or fill with plastic cement.

Don't try to repair a leaky aquarium while it is full by applying waterproofing solutions to the outside seams. This has never been known to work.

Covering for the floor of the aquarium is far more important than you might suppose. The ideal covering is sand of medium coarseness, the grade used for making concrete. This remains loose enough at all times for the roots of aquatic plants to spread and draw sustenance from it. Use a 1- to 2-inch layer of it.

Fine sand packs down and becomes too hard for roots to penetrate. Coarse sand is to be avoided if the particles are large enough to hide fish droppings and bits of food. Such tiny scraps, if the snails or fish can't find them, decompose and foul the water. For this same reason, pebbles, small stones, and marbles-regardless of how pretty they look-are to be avoided.

Now and then the sand will become dark and foul-smelling, for no apparent reason. More often than not, I suspect, this is a result of insufficient sunlight. Aquarium plants which get the required two hours usually do a good job of drawing enough food material from the aquarium floor to keep the sand sweet. Try giving the aquarium a little more sun if this trouble develops. In the meantime, the sand can be sweetened quickly by rinsing to remove all foreign matter, and then spreading it out on a newspaper to dry in the sunshine.