Fischbuch is a fictional book featured in the Cthulhu Mythos stories of Brian Lumley, first mentioned in "Name and Number".
In the Mythos[]
Authored by Konrad von Gerner in 1598, Fischbuch is a tome of "oceanic lore and legend", comparable to Gaston le Fe's Dwellers in the Depths and Gantley's Hydrophinnae. Occultist Titus Crow owns a copy (EXP: "Name and Number"), as does the wizard Julian Carstairs (EXP: Lord of the Worms).
Behind the Mythos[]
The name of the book's author, Konrad von Gerner, is similar to the real 16th century naturalist Conrad Gessner, who did author a book named Fischbuch, although not in 1598.