Breeding Polypterus Endlicheri

[Koji™]

Article by : Hiroshi Azuma

Breeding Polypterus Endlicheri
For a long time now I have been interested in the so-called "ancient fishes". Although I have bred many difficult fishes over the years, I have always devoted part of my time to the study and breeding of arowanas, lungfishes.
Among my favorite ancient fishes have been the bichirs, genus Polypterus. In the February, 1986 issue of TFH, I reported on my success in spawning and rearing Polypterus ornatipinnis. At the same time, however, I was working with P.endlicheri, a large bichir from central Africa.
Patience is definitely needed to work with any of the ancient fishes, because most are slow-growing, long-lived, and take few years to reach sexual maturity. I started working with P.endlicheri in 1986, and I was not completely successful until just last summer.

Background
The Polypteridae is a small family of African freshwater fishes. It contains two genera: Polypterus (bichirs) and Erpetoichthys (ropefish). All the polyterids are elongate and cylindrical with snake-like heads, tubular nostrils, and a heavy armor of bony ganiod scales. The spiny portion of the dorsal fin is divided into numerous finlets, each finlet comprised of one spine and the associated fin membrane; all other fins have fleshy bases and are extremely flexible.

A feature that the polypterids share with many other ancient fishes is the ability to breathe atmospheric air. The swim bladder has two lobes, the right one larger than the left ; they are joined at the front to each other and to the esophagus. The fish can swallow a gulp of air into the swim bladder, where oxygen can be absorbed through the blood vessels lining its interior. The swim bladder is not a true lung, but it certainly comes close.
The members of the genus Polypterus mostly inhabit the weedy margins of rivers, lakes and marshes. They are predatory feeding mostly on smaller fishes, but amphibians, insects and crustaceans may also be taken.



Polypterus breed during the rainy season, from about July to September. When in spawning condition the fish are relatively easy to sex, as the male has a larger anal fin. The eggs are laid in plants, and when they hatch the young adhere to the undersides of plant leaves using special cement glands that recede when the larvae become free-swimming. The larvae have large external gills and look similar to newt larvae or other aquatic salamanders. These are gradually resorbed as the fish grow, and are totally absent in adults.

P.endlicheri is widely distributed in central African but tends to inhabit the drainages of large rivers and lakes such as the White Nile, the Volta River, the Niger River, and the Lake Chad. It can grow to about 25 inches (63cm). The body is distinctly flattened, at least anteriorly. There are species similar in coloration. such as P.delhezi, but there are details of fin and scales counts that will serve to confirm the identity of P.endlicheri. Specially, P.endlicheri has a dorsal fin with XI-XIV spines (as you may know, fin spines are denoted by Roman numerals). There are 50-58 scales in a longitudinal row.