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.
Practical Natural History OF FRESH WATER FISHES, AMPHIBIANS, INSECTS, ETC.,
AND AQUATIC PLANTS;
With a View to their Culture, and Hints for the Successful Construction, and
MANAGEMENT OF AN AQUARIUM.
PROFUSELY ILLUSTRATED WITH PLATES AND WOOD CUTS, DRAWN FROM LIFE.