Q. I recently acquired a fish that I know nothing about, not even the name. My fish looks like a miniature gar.  I have not been able to find out anything about my fish from any books. While visiting the Tennessee Aquarium today, I saw a fish like mine, but its name was not posted. Please help me by answering the following questions. What species is it and where does it come from ? How long does it live and how big does it get ? Is it a livebearer or an egg layer ? How do you distinguish male from female? What are the best water can be conditions and food ? What other fish can be placed in with it? What size tank should it be in ? * Brad Fever, Kansas

A. Despite its looks, the halfbeak is a quiet aquarium species. There are several entirely different fishes that could be described as “miniature gar” but the type that was illustrate in the above issue was a halfbeak. This a well-known variety of aquarium and should be in most books under its common name or under its scientific name, Dermogenys pusillus. Not a gar.  I’ll provide the basic information on this fish but I suggest that you also look it up in another reference to make sure we are talking about the same species. The halfbeak, or as it is sometimes called, the wrestling halfbeak, is a member of the family Hemirhamphidae. This is a worldwide family and there seem to be about 70 members in this fish family most of which are strictly marine. Some members grow to be about 18 inches in length but most stay much smaller. The common aquarium halfbeak and its closest relatives come from the fresh and brackish water habitats of coastal Southeast Asia and grow from 3 to 5 inches length. If maintained properly, this is a hardy and interesting species that will live 2 1/2 to 3 years and will produce enough off-spring to keep the tank going indefinitely. If they are not properly maintained, they can, and will, die in a very short time.

It is a livebearing species, in which the male has a modified anal fin that can roll into a tube, enabling it to insert a sperm packet into the vent of the female, where the ripe eggs are fertilized. The eggs go through their maturation process in 20 to 60 days, depending upon the water temperature. When the water is kept very warm, the shortest amount of time elapses, but the fewer successful fry are produced. I have found that temperatures in the mid 70 to 80 degrees Fahrenheit are best for this species and produce the highest number of live fry. There are two very important “secrets” to successfully maintaining the halfbeak.

The first has to do with the water. It should be moderately hard and slightly alkaline a hardness of 10 to 15 DH and a pH of 7.0 to 7.5. There should also be a moderate amount of salt added to the water. (I use seawater at the ratio of 2 quarts of seawater in 10 gallons of freshwater. Others recommend 1 tea-spoonful of rock salt per gallon of water. We’re about the same but I use my method because the salt in the seawater is pre-dissolved and easier to mix.) There is yet another part to the water “secret.” The wrestling halfbeak is a small, slender, shoaling fish that is adapted to surviving in the shallow, heavily planted margins of water courses. The ideal aquarium provides as much surface area as possible but depth is unimportant. While I have successfully used a 5-gallon aquarium for a single pair, I tend to use a 15-gallon tank filled to the halfway mark and then stuff it with a large amount of floating watersprite.

This will house three trios comfortably. This has the added advantage of keeping the fish in the tank. Halfbeaks are prone to jumping but they are not good enough to get out of this type of setup. The second major “secret” is that half beaks are very shy by nature they get spooked easily. When they are frightened their reaction is to flee. But they are not very bright. They do not understand glass sides and wild-caught specimens never seem to learn (tank-raised fish have a better “understanding” of their situation). The danger in this condition is that they can damage their beaks in their hysterical flight and the damage can be severe enough to cause death.

The best way that I have found to handle this condition is to decorate three sides of the aquarium with a rim of live, rooted plants and cover the sides and back with paper or tank backing. Keeping this in mind, it points to the fact that they should not have boisterous tankmates that will stimulate the flight reaction. It is my opinion that this species does best in a single species aquarium and, at this point, considering its water preferences and its shy nature, I cannot think of another species I would be willing to put it with in a community situation. The other halfbeaks have similar special needs so if you intend to acquire one of these, learn as much as you can about it before you buy it. The same goes for every type of fish.