A CURIOSITY OF THE LIVE-BEARER WORLD
The Half-beak or Dermogenys/Belonsox
A SHORT HISTORY
Two very strange live-bearing fishes that are sometimes kept in an aquarium are Dermogenys and Belonesox. The family Hemiramphidae (Half-beaks) is common throughout tropical seas, but Dermogenys pusillus inhabit the brackish rivers of Malay, Siam and the Dutch East Indies. These unusual fish can be kept and bred in a fresh-water aquarium, especially if a little salt (a teaspoon per gallon) is added.
The lower jaw is fantastically prolonged: if both jaws were the same length the fish would appear to have a long beak; as it is, it only has “half-a-beak”, thus the common name. The halfbeak is a superb fighter, the second in ability only to the fighting fish itself. The people of
Thailand have, for many years bred halfbeaks for fighting, until the present cultivated strain far outperforms its wild counterpart.
Fights are staged in this way: Two halfbeaks are placed in a shallow earthenware bowl, filled with a few inches of water. The fish eye each other for a moment and then close in for the attack. They may lock jaws and shake and roll over. Or one fish may clamp its large jaws over the other fish’s head. Obviously, the fish that grabs the other has a temporary advantage. Such “wrestling” sometimes continues for hours, until one of the combatants becomes too exhausted to continue. The one who gives up is the loser, and the men who have placed their bets on this fish lose as well. Occasionally, both contestants become exhausted at the same time. That is, the fish administering the most holds during the fight scores the larger number of points and is declared the winner!
In Southeast Asia and the East Indies, where the halfbeak is native, it is a valuable eater of mosquito larvae. If the quiet streams, ditches and ponds where the halfbeak lives were without this fish, the mosquito population would become unbearably large.
Halfbeaks make interesting aquarium pets, and they ordinarily do not fight with other kinds of fishes their own size. However smaller fishes are likely to be eaten quickly!
THE BREEDING PROCEDURE
The Halfbeak is not at all a beautiful creature to have about the house, nor is it an easy fish to breed in captivity, but there is a certain fascination in watching anything as weird as this. The adult male is about three inches long and the female, who is considerably larger, produces young in litters varying from one to thirty at a time, which are anywhere from 1/4 of an inch to over and inch at birth! The babies grow rapidly, especially if there are plenty of live plants for them to tear up and devour, and begin to develop the half –beak when they are about four weeks old. The tank must be thickly planted so that the babies can hide in the green water-grass before their parents can eat them.
Since the males, when two or more are together, will fight, sometimes to sever harm or death, it is best to keep only one male with several females for breeding purposes. The females are easily recognized by their fan shaped anal fin. For a successful brood, the pregnant female must be left undisturbed; in favorable conditions, not in a room with traffic, but away in a private corner. The female may bred every 4 to 8 weeks. Before she gives birth, put brown paper around the bottom half of the tank or the babies may swim into the glass not seeing it and damage their prominent jaw. This problem can be avoided by using aquatic plants to form the borders or confines of the tank.
To keep these fish it is necessary to have a constant supply of live food for them such as guppies or tadpoles. Without constant live food of substantial size, they will quickly die. Many breeders keep a tank of these unusual fish around the breeding room to dispose of their “cull” or less than ideal fish in this manor. Many fish fans hate to use live fish as food, but true aquarists and breeders know that this is only a part of nature.