폴립테루스 번식정보...

[모다피]

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.

 

The Beginning
My odyssey with P.endlicheri began in December, 1986, when I received seven specimens. They had taken a roundabout route starting with the African collector, who sold them to a German wholesaler, who sold them to a Japanese importer/exporter, who finally sold them to me. The fish were young, perhaps no more than a year old, and were about 8 inches (20cm) long.





From that point on there was not much to report for a long time. The fish were kept in a tank measuring 60 x 24 x 24 inches (150 x 60 x 60 cm), which held about 150 gallons (570 liters). The temperature ranged from 79-84°F (26-29°C), the pH was 4.8 to 6.0, and the general hardness was 5-7 degrees. I changed about half the water once a month. I fed the fish both live and freeze-dried bloodworms, freeze-dried krill, and small live fishes, usually goldfish. Although all species of Polypterus like live fishes in their diet, I have found them to be very adaptable, and most will take dried foods and flakes. This was pretty much routine from December, 1986, to April, 1992, except that as the fish approached full size they were moved to a tank measuring 72 x 24 x 24 inches (180 x 60 x 60 cm), but only partially filled (about 130 gallons).

 

 

Courtship
In April of '92 I knew something was happening. My female P.endlicheri began to develop noticeably heavy abdomens. At this point the males wasted no time in pursuing the females. The male spreads his anal fin and begins to nip at the body, tail and anal fin of the female. There may even be some soft nipping at the female's head. Overall, the male's actions are quite gentle, and do not pose a threat to the female. This behavior was quite similar to that I observed when i bred P.ornatipinnis.



The First Spawning
Over the course of three days, 13-15 June 1992, my fish spawned for the first time. A pair consisting of a male 19 inches (48cm) long and a female 21 inches (53cm) long had gotten together. They kept some distance between themselves and other fish. As mentioned previously, the male had an anal fin much larger than that of the female. Even without the size difference, it was easy to tell the sexes apart. Spawning was quite protracted, taking place from about 9:00 AM to 7:00 PM. As i said, this was repeated three days. Hundreds of eggs were laid; I count not tell how many. Unfortunately, they all went bad. Obviously, they had not been fertilized. Was the male too young? I thought this could have been the case. The conditions in the spawning tank had been optimal: temperature, 82°F (28°C); pH, 5.8-6.0; hardness, 5.0 dGH. Since I could not fault the water as far as I could tell, it seemed logical to assume that the problem was with the fish, which led me to my theory that the male was not ready.



The Second Spawning
I would have to wait over two years before there was any more spawning activity. Over that period of time conditions were fairly stable, but a few small changes were made---some by me, and some by chance. I had added a small floating island to the tank, plant semi-aquatic and emersed vegetation. In other words, I had created what you might call a very wet aqua-terrarium. Also, there was a bit more filtration and aeration than before. I used two large canister filters, and airstone buried in the gravel beneath a funnel, and a large side box filter. The water had a moderate current and was very clean and well-aerated. Finally, most of the time the water temperature was a little warmer because we had a very warm summer in '94.
On 16 and 17 August 1994, there was more spawning. The water temperature ranged from 82 to 84°F (28-29°C) over the two days. The pH was 5.8-6.0, the hardness 3.0 dGH, and the conductivity 230-280 microSiemens. The tank was planted with Java fern (Microsorium pteropus) and also contained rocks and driftwood. Light was provided by two 40-watt fluorescent tubes that were on a 9:00 AM to 9:00 PM timer, and the tank also received some daylight through a window.




Courtship proceeded as before; at the end of these maneuvers, the male actually cupped his anal fin over the female's anal fin and vent. The eggs were laid directly into the male's curled anal fin, I can presume that this is an adaptation to concentrate the sperm as much as possible to ensure fertilization. One spawning act would take about 3-5 seconds, during which the female would lay about 3-8 eggs. The fish would pause momentarily and then repeat the action. As before, spawning began at about 9:00 AM and ended about 7:00 PM, but the peak of spawning activity was in the late afternoon. The first day, they laid about 300-500 eggs, and on the second day their production was down to about 100-150. After that, they were apparently done.

 

 

Hatching
The eggs were demersal (sinking), about 2.5 to 2.8 mm in diameter, and brown to chrome yellow in color. They were deposited on plants, wood, rocks, whatever. I quickly moved as many eggs as I could to a hatching tank, which filled with my local tap water. The temperature of the hatching tank was 82-84°F (28-29°C), the pH about 7.0, and hardness about 4 dGH.



Some 58-70 hours after fertilization, about 350 hatched. A large number of eggs again proved infertile, but as least there were enough so that I got large number of fry despite this. Two cement organs were visible on the undersides of the heads of the fry, and they used these to cling to a nearby surface for an additional three days before becoming free-swimming. The fry were about 0.36 inch (9 mm) long when they became free-swimming. They accepted live brine shrimp nauplii. Six days after that, I added chopped tubifex worms to their diet. At this point the fry were about 0.6 inch (15 mm) long, and had very large external gills.

 

Fries
A disconcerting thing happened next. The fry developed strong cannibalistic tendencies. They devoured one another whenever possible, and even when it was not they would bite and injure each other. Many of bitten juveniles developed fungal (Saprolegina) or protozoan infestations and died.



Alarmed that I might lose the fry I had worked so hard to obtain, I decided on two strategies. First, I placed one of the largest and most robust fry in a small tank by itself, so that I could be sure of having at least one that none of the others could get at. Next, I placed the remainder of the fry into a large tank, heavily planted with Glossostigma and Fontinalis. I reasoned that perhaps their aggression was intensified by crowding, and hoped that the extra room and places to hide would help. I found that while the cannibalism continued, it was not as bad, and this behavior peaked at an age of about 30-45 days, when the fry were about 1.1-2.6 inches (2.8-6.5 cm) long.



Growth continued as follows. At 70 days of age the fry were 3.8-4.2 inches (9.5-10.5 cm), and had begun to eat bloodworms and small fishes in addition to the tubifex they had been getting. At 180 days they were 5.2-6.0 inches (13-15 cm) long and were eating larger fishes such as goldfish. At 300 days they were 6-8 inches (15-20 cm) long and were eating goldfish, crawfish, shrimp, grasshoppers, crickets, earthworms, mealworms, air-dried and freeze-dried krill, and prepare food sticks.

 

 

귀중한 정보지만 제가 영어에는 젬병이여서요^^

 

대충 그림보면 알겠는데....

 

폴립유생은 도롱뇽과 매우 흡사 하군요.

 

새끼뿐만 아니라 여러모로 도롱뇽과 비슷하네요

 

알도 양서류랑 비슷하게 젤라틴으로 싸여있고 말이죠^^

 

 

[이무기]

양이 얼마 안된다면 제가 번역 해봐야지 했는데 장난 아닌데요 ㅠ.ㅠ 좋은 정보 감사합니다 즐물 하세요.

[룰룰랄라(탈출!)]

? ????????????????????????????? ?????????? 뭔말이지????????????????????????????????? ??????????????????????????????????? ???????????????????????????

[룰룰랄라(탈출!)]

싹다 쏼라쏼라네

[천사아찌]

좋은 정보 감사합니다. ^^

[chaewoon]

ㅎㅎ좋은정보~~그림만보구 적당히 이해,,ㅋㅋ

[메기쫗아~!]

ABCD같은것도 겨우 칠판에 적을정도인데 이거정말 너무하네요;;ㅎㅎ 그림보니....고기가 붙기만하면 되는것같은데..그건 어떤생물이든 마찬가지아닌가?>ㅎㅎ

[갑각류매냐]

제길 영어다