"All kinds of fishes and fish-eggs are subject to the attacks of such fungus, especially after having been even slightly scratched or injured. As a consequence, the lamprey attacks on fishes cause wounds that often become the seat of a slowly spreading but fatal fungus. We have seen many nests of the bullhead, or horned pout (_Ameiurus nebulosus_), with all the eggs thus destroyed, and we have found scores of fishes of various kinds thus killed or dying. It is well known that in many rivers this is the apparent cause of great mortality among adult salmon. Yet we really doubt if it ever attacks uninjured fishes that are in good strong physical condition which have not at least had the slime rubbed from them when captured. It is contagious, not only being conveyed from one infested fish to another, but from dead flies to fishes." (For a further discussion of this subject see an interesting and valuable Manual of Fish Culture, by the U. S. Fish Commission, 1897.) =Earthquakes.=--Occasionally an earthquake has been known to kill sea-fishes in large numbers. The _Albatross_ obtained specimens of _Sternoptyx diaphana_ in the Japanese Kuro Shiwo, killed by the earthquakes of 1896, which destroyed fishing villages of the coast of Rikuchu in northern Japan. =Mortality of Tilefish.=--Some years ago in the Gulf Stream off Newfoundland an immense mortality of the filefish (_Lopholatilus chamæleonticeps_) was reported by fishermen. This handsome and large fish, inhabiting deep waters, died by thousands. For this mortality, which almost exterminated the species, no adequate cause has been found. As to the destruction of fresh-water fishes by larger enemies, we may quote from Professor H. A. Surface. He says there is no doubt that these three species, the lake lamprey (_Petromyzon marinus unicolor_), the garpike (_Lepidosteus osseus_), and the mud-puppy (_Necturus maculosus_), named "in order of destructiveness, are the three most serious enemies of fishes in the interior of this State [New York], each of which surely destroys more fishes annually than are caught by all the fishermen combined. The next important enemies of fishes in order of destructiveness, according to our observations and belief, are spawn-eating fishes, water-snakes, carnivorous or predaceous aquatic insects (especially larvæ), and piscivorous fishes and birds." The lamprey attaches itself to larger fishes, rasping away their flesh and sucking their blood, as shown in the accompanying plate. [Illustration: FIG. 233.--Catfishes, _Ameiurus nebulosus_ Le Sueur, destroyed by lampreys (_Petromyzon marinus unicolor_ De Kay). Cayuga Lake, N. Y. (Modified from photograph by Prof. H. A. Surface.)] CHAPTER XX THE MYTHOLOGY OF FISHES =The Mermaid.=--A word may be said of the fishes which have no existence in fact and yet appear in popular literature or in superstition.