This section is from the book "The Goldfish And Its Systematic Culture With A View To Profit", by Hugo Mulertt. Also available from Amazon: The goldfish and its systematic culture.
Not many of these are necessary for the raising of goldfish. In addition to the ordinary gardening tools used in constructing and repairing the ponds, four sizes of dip-nets should be kept near at hand. 1st. A large one consisting of a heavy iron wire ring, about the thickness of a lead-pencil, and measuring about fifteen inches in diameter. This ring is securely fastened to a hickory pole seven feet in length, and covered with heavy mosquito netting, the bag to be about twelve inches deep.
2nd. A medium-sized dip-net of oval shape, measuring six inches by ten inches through the center. This is best made of No. 10 brass wire, fastened to a handle four feet in length, and covered with finer mosquito netting, forming a shallow bag similar to the bowl of a spoon. This net is used to remove insects and small fish from the water.
3d. A hand-net of the same size and material as No. 2, with this difference, that the handle may be made of the same wire that forms the frame.
4th. A small dip-net, also made of brass wire, No. 16 or 17, in this case of sufficiently small size to use in removing fish or insects from the hatching-jars.
Several one-gallon candy-jars for hatching the eggs; several tin buckets of different sizes, for carrying and removing fish; a yard or two of mosquito netting; some wire netting of the same mesh as that used in the guards on the outlets; a thermometer, a couple of musk-rat traps, if needed, and a gun to dispose of snakes, birds, etc., complete the outfit that is necessary for the proper performance of the work in hand.