While building tank No. 2, keep watch for eggs in the spawning tank. Laying begins late in April or early in May outdoors. The egg is no bigger than a pinhead, yellow, or cream-coloured. Look for them on the plants. Snip the twigs off with great care and transfer the eggs, twigs and all, into large candy jars in clean water; one hundred eggs is enough for a gallon jar. Be careful that the water is of the same temperature in the jar as in the tank. Eggs should be kept not lower than sixty degrees Fahr., and not higher than ninety degrees Fahr. They hatch in two or three days or at most in less than a week. Do not disturb the water. Sudden changes of temperature will kill the young fish.
When the fish are three days old, they are pretty lively and will soon begin to need other food than that supplied by the egg. To transfer them from the "incubator" to the rearing tank is a delicate operation. Mr. Mulertt advises putting the tiny fish into a small, shallow, "nursery" tank first to make the change more gradual. The jar can be emptied very gently, fish and all, into this tank.
Prepare the rearing tank, taking every precaution against enemies. It should be covered with a screen to keep the dragon flies from laying their eggs in the tank. Dragon fly nymphs are death on new-hatched goldfish. If the fish get a good start they will hold their own. Let me warn you again to take great precaution against chilling the fish. A few degrees difference may be fatal. When the fish are a week to ten days old, they should be about a half-inch long, darting swiftly about in the nursery tank. Be sure the temperature of the water is right, then set a wide-mouthed pail or jar full of water down in the tank with the fish, and dip the biggest one at a time with a little hand net of soft material. Do not crowd the fish in the transfer pail, but rather make more frequent trips. Extremely delicate handling is absolutely necessary. Do not dip the fish out of the jar, but put it down in the water deep enough so they can swim out of their own accord. They are to stay a long time in the rearing pond so must not be crowded. In a tank covering an area of one hundred and sixty square feet, two hundred to three hundred fish can be reared. When they are only one half an inch long, the tank looks thinly settled, but they soon grow.
The young are silver-gray at first. They usually get their permanent colour before reaching the age of two months. In warm ponds, in sunny weather, goldfish may grow to be six inches long in the first summer, but between two and three inches is more normal.
Goldfish in outdoor rearing ponds do not require artificial feeding. Nature supplies them with their natural food.
The storage tank is simply to keep the fish in while awaiting purchasers. It should be divided by partitions into small compartments. It is convenient to sort the fish taken from the rearing tank, so that those of one size or colour or variety can be separated and buyers can readily see the stock. It is easier to catch them in the small tank also. In the storage tank some feeding is usually needed. Fresh, dry bread crumbs are recommended by most fish growers; feed small amounts until they get used to it and until you know just how much they require.
The winter pond costs the most to build. It should be three feet or more deep, lined with boards or cement, and located so that water will be moving through it, in and out slowly all winter, to prevent freezing. It should be covered during storms. Growers plan to get rid of their stock except breeders before winter sets in. One can dispense entirely with a winter tank if he can establish a house aquarium successfully for wintering the fish from which he expects to obtain spawn the following spring.
As might be expected of animals which have for so many centuries been associated with man, goldfish have a good many diseases. Their ill-health can almost invariably be traced to neglect or ignorance on the part of the person upon whom they are dependent. The signs of ill-health are usually quite noticeable. They are: Faded colours, bloody streaks, coated or inflamed fins, and swollen gill covers. Most of the troubles have to do with air supply. When a fish loses colour and appetite, has a slimy coating, and acts weak and dejected, it should be put into a "hospital" aquarium where plenty of plants are flourishing, at a temperature of seventy to eighty degrees Fahr. One teaspoonful of salt to each gallon of water will be good for the fish, but no food should be offered for several days. This remedy will usually restore the fish if its trouble is asphyxia or itch and has not gone too far. In the open water conditions right themselves more readily, but fish acting queerly should be taken out from among the others.
The greatest harm may result from hail storms and heavy rains on unprotected tanks. The natural enemies of goldfish inhabit the same ponds and to succeed one must daily wage war against crayfish, tadpoles, salamanders, snakes, fish-eating birds, muskrats, and aquatic insects. Toad and frog spawn found in goldfish ponds should be removed to some other pond to mature. These creatures are useful as destroyers of insects but you can dispense with them in goldfish tanks.