The Trachichthyidæ are deep-sea fishes with short bodies, cavernous skulls, and rough scales. The dorsal is short, with a few spines in front. The suborbitals are very broad, often covering the cheeks, and the anal fin is shorter than the dorsal, a character which separates these fishes from the Berycidæ, in which group the anal fin is very long. The belly has often a serrated edge, and the coloration is red or black, the black species being softer in body and living in deeper water. Species of Hoplostethus, notably Hoplostethus mediterraneus, are found in most seas at a considerable depth. Trachichthys, a genus scarcely distinguishable from Hoplostethus, is found in various seas. The genus Paratrachichthys is remarkable for the anterior position of the vent, much as in Aphredoderus. Species occur in Japan and Australia. Gephyroberyx, with the dorsal fin notched, is known from Japan (G. japonicus) and Madeira (G. darwini).
We may also refer to the Trachichthyidæ certain species of still deeper waters, black in color and still softer in texture, with smaller scales which are often peculiar in form. These constitute the genera Caulolepis, Anoplogaster, Melamphaës, and Plectromus. In Caulolepis the jaws are armed with very strong canines.
Allied to the Trachichthyidæ are also the fossil genera Hoplopteryx and Homonotus. Hoplopteryx lewesiensis, from the English chalk, is one of the earliest of the spiny-rayed fishes.
Fig. 201.—Paratrachichthys prosthemius Jordan & Fowler, Misaki, Japan. Family Trachichthyidæ.
The Soldier-fishes: Holocentridæ.—The soldier-fishes (Holocentridæ), also known as squirrel-fishes, Welshmen, soldados, matajuelos, malau, alehi, etc., are shore fishes very characteristic of rocky banks in the tropical seas. In this family the flesh is firm and the large scales very hard and with very rough edges. There are eleven spines in the dorsal and four in the anal, the third being usually very long. The ventral fins have one spine and seven soft rays. The whole head and body are rough with prickles. The coloration is always brilliant, the ground hue being scarlet or crimson, often with lines or stripes of white, black, or golden. The fishes are valued as food, and they furnish a large part of the beauty of coloration so characteristic of the fishes of the coral reefs. The species are active, pugnacious, carnivorous, but not especially voracious, the mouth being usually small.
Fig. 202.—Soldier-fish, Holocentrus ascenscionis (Osbeck).
Fig. 203.—Soldier-fish, Holocentrus ittodai Jordan & Fowler. Riu Kiu Islands, Japan.