Because the main propagation period of common carp is in September, but the demand for fingerlings appears from middle of November lasting end of January or longer, it would be worthwhile to find ways to extend the propagation time in October and November for the interest to spare keeping costs, losses, longer time for utilisation of hatchery and nursery facilities, etc…
The keeping conditions of the breeders are very poor and unsuitable in Andasibe and in Sisaony, but most probably in the other stations as well. The female breeders are congested in small ponds where sometimes less than 10 m2 space is available for a 3–5 kg breeder. The natural food is lacking for the breeders because the uncontrolled number of invaded Tilapias which compete successfully for the natural food with the clumsy carp. The feed offered for the breeders does not content the necessary ingredients to build up the egg mass in the ovary.
Although eggs can be gained even in December, the viability of the eggs and larvae becomes poorer and poorer. Many eggs (sometimes 100%) used to die after a normal cleavage during their development. Others go through the first stages of embryo development and die after. Many embrios' body become defective, they die after or during hatching. The survival rate of the just feeding (3 days old) fry becomes lower and lower in the nursery ponds. The mentioned signs are typical showing the lack of essential materials (vitamins ? aminoacids ? minerals ?) in the female breeders' diet.
It was observed that the female carps never develope as many eggs in the ovary as the breeders used to in Hungary (100,000–200,000 per kg bodyweight). It is due to the unsuitable feed and the lack of ample natural food.
Although the induced spawning was successful seemingly in October and November in Sisaony, the kakabans were covered with plenty of eggs, but most or all of them died during the egg development stages. It shows that although normal ovulation occured but the eggs became materially incomplete so they could not pass through the embryo development.
The table below shows the gained eggs, the just feeding fry, and survival rate of one month old fingerlings, in Andasibe Experimental Station.
| Date of propagation | Temp. night-day C° | No. of injected females | Total weight kg (min-max) | No. of ovulated females | Stripped eggs g. No million | No. of 3 days fry | Cropped after (x) days No | Survival rate % |
| 17/10 | 21–26 | 10 | 36 (2.5–6) | 9+ | 2060 1.6 | 301000++ | 41. 139270 | 46.3 |
| 13–14/11 | 22–27 | 5+5 | 40.3 (3.2–5) | 8 | 3170 2,5 | 290000 | 28 39970 | 13.8xx |
| 5–6/12 | 24–27 (22–24)* | 6+6+7 | 64.8 (1.5–4) | 2+3+3 | 1860 1.5 | 19500 | 28 5203 | 26.7 |
| 10/1 1980 | 23–28 | 6 | 8 | 3 | 200 0.16 | 4990 | 22 423 | 8.5% |
+ one died by injuries.
++ it was stocked 20–24 thousand in 1 are ponds, 40000 in 10 are ponds.
x 300000 developed eggs were transported to Sisaony (see APPENDIX No 2)
xx nursery ponds were cropped short before ; preparation of nursery ponds were unsatisfactory.
* very bad fertilisation or no fertilisation at all.
Conclusions :
Success promising artificial propagation can be made in September and October in Andasibe (in Sisaony only in Sept.) among the present keeping and management circumstances.
The feeding of the breeders are unsatisfactory. Feed mixture available in the local market has not the essential ingredients.
Some breeders are too old and too heavy, not suitable for artificial propagation (The ideal weight of females for artificial propagation is 2.5–4 kg).
There is a Hungarian experience that keeping the females in warm (23–26 C°) throughflowing water in small cement concrete tanks (ample oxygen provision prevents the ripe eggs from resorption) feeding with full valued protein rich (30%) feed, daily ration 2–2.5% of the body weight, the dormant developing stage of the occytes (eggs in the ovary) can be extended quite unlimited. This experiment could be repeat in Andasibe in the cement concrete tanks (water filter tanks) equiped with turning pipe to charge continucusly the bottom water.
It is recommended :
To keep the breeders according to a new management system in bigger ponds as recommended in the chapter V.
To sort out the too old breeders and refresh the breeders' stock with young ones.
Try to repeat the Hungarian experiences in the mentioned filter tanks with 20–30 breeders (females).
It would be worthwhile to make further trials for the interest of extension at least one month longer the propagation period. Possibilities to try :
FOR COMPARISON there are the basic data (standards) of artificial propagation and nursing of common carp in HUNGARY.
(10 years average of a well managed hatchery).
The ratio of sexes for artificial propagation : 2 females, 1 male ; 2:1.
The weight of the females : 3–5 kg.
Percent of the ovulating females after hypophysation : 60–90%.
“Dry” eggs produced by one stripped female in g. : 500–1000.
One stripped male provides milt : 10–20 cm3.
1000 g. “dry” eggs need 5–10 cm3 milt for fertilisation.
Fertilisation rate : 80–90%.
Hatching rate of the fertilised eggs : 90–95%.
Survival rate of the larvae up to air taking (first feeding) : 90–95%.
Expected just feeding fry (3–4 days old) from 1 kg “dry” eggs : 500,000–700,000 fry.
Stocking rate into the nursery ponds : 200–400 fry per m2.
The nursing time : 21–28 days.
Size of the fingerlings when nursing ended (standard length) : 2.5–3 cm.
Survival rate during the nursing time : 50–60%.
