Field Document 3
March 1990




A report prepared for the project Fisheries Development in Qinghai Province


László Váradi
Aquaculture Engineer

This report was prepared during the course of the project identified on the title page. The conclusions and recommendations in the report are those considered appropriate at the tims of its preparation. They may be modified in the light of further knowledge gained at subsequent stages of the project.

The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the United Nations or the Food and Agriculture Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.

Rome, 1990

Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.

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2.1 Biological Criteria

2.2 Strategy for Artificial Reproduction

2.3 Facilities Required for Artificial Reproduction of Naked Carp

2.3.1 On-site Pilot Scale Hatchery

2.3.2 Large-scale Hatchery

2.3.3 Nursery Ponds

2.3.4 Transporting Equipment


Appendix 1: Recommended Literature to Assist in the Development of Technology for Artificial Propagation, Larvae and Fingerling Rearing of Naked Carp

Appendix 2: List of Equipment for the Experimental Naked Carp Hatchery


1. Major Reproduction-Biological Data of Naked Carp Gymnocypris przewalskii przewalskii (Kessler)


1. Qinghai Lake and its surroundings

2. General layout of the on-site pilot scale hatchery complex

3. Layout of the hatchery

4. Cross section of the hatchery

5. Tank for spawners

6. Details of the hatching jars

7. Details of the larvae rearing tank

8. Closed pressure filter


The Government of the People's Republic of China, assisted by the United Nations Development Programme and the Food and Agriculture Organization of the United Nations, are engaged in project CPR/88/077, Fisheries Development in Qinghai Province.

As part of project operations, FAO assigned Dr L. Váradi as aquaculture and drainage engineering specialist from 24 May to 21 June 1989 with the following terms of reference:

However, due to the unforeseen difficulties in China, the mission had to be cut short, and the consultant returned to Rome on 11 June.

The terms of reference were consequently amended, and efforts were concentrated on planning of the naked carp hatchery.



Knowledge of the reproductive biology of naked carp is limited, but key data useful in planning a strategy for artificial rearing of the species are summarized in Table 1.


To date, no attempts have been made at the artificial reproduction of naked carp in Qinghai Province. However, the local experts have information on the successful small-scale propagation of this species in the Fisheries Research Institutes of Hei Longjian and Inner Mongolia. Future cooperation with these institutes is highly recommended.

The main spawning areas of the naked carp are in the Buha river, especially near the Bridgehead shown in Figure 1.

Mature spawners could be captured here, then transferred to an onsite pilot scale hatchery where eggs and milt would be collected and the eggs fertilized. After stripping, the spawners could be kept in tanks for a time to recover and then be released back into the river.

After a time the fertilized eggs become more resistant to handling and transport. The eggs could then be packed in special polystyrene boxes as used for transportation of salmonid eggs, for delivery to a large-scale hatchery. It is proposed that this will be established as an integral part of the existing hatchery of the Fisheries Research Station in Xining, where adequate infrastructure and experienced staff are available. For the incubation of eggs 8-1 Zug jars are recommended, and the larvae can be kept in 200 1 larval rearing tanks from hatching until the larvae fill their swim bladders with air and their mouths and gills become fully developed.

Table 1

Gymnocypris przewalskii przewalskii (Kessler) 1

Time needed for sexual maturation7 years
Size of mature fish35–40 cm
Average number of eggs/breeder16 242 eggs
Spawning seasonMarch-July
Water temperature range during spawning6–17.5°C
Sex ratio (female:male)1 : 2–1 : 3
Spawning areaShallow (0.1–1.1 m) transparent water with sandy-gravel bottom, slow but constant water flow
Spawning habitFish of different size and age spawn in the spawning area following upstream migration
Size of the dry eggs2.5 mm
Size of the swollen eggs4.5 mm
Average weight of the swollen eggs(28.75 eggs/g)
Incubation time from fertilization to hatching at 15.5°C112 hours
(72 day-degree)

1 Data derived from the publication “Fish distribution in Qinghai Lake and the biology of naked carp” by the Biological Institute of Qinghai. Published by the Scientific Publishing Company, Beijing, 1975 (in Chinese)

In order to obtain a higher survival rate, the larvae should be nursed in earthen nursery ponds for several weeks before they are transported back to the natural environment for release into the mouth of a river flowing into the Qinghai Lake.

Although incubation facilities used for trout might also be suitable for the incubation of naked carp eggs, the establishment of a separate, special naked carp hatchery is recommended.

In order to develop a usable technology for artificial propagation and for larvae and fingerling rearing, extensive research and development work is required. The hatcheries must be equipped with the necessary instruments for this. The literature listed in Appendix 1 is also recommended for reference during this experimental work.


The design recommended for the naked carp hatchery is based on the following parameters:

The naked carp hatchery will not consist of one facility only, but will comprise a complex of several components as follows:

2.3.1 On-site Pilot Scale Hatchery

The major purpose of this facility is to provide adequate conditions for the collection of the eggs and sperm, for the fertilization of the eggs and for the preparation of the fertilized eggs for transport.

However, there are also possibilities to incubate the eggs and to rear the larvae on an experimental scale here.

Since this facility should be set up near the main spawning area of the fish, as close as possible to the river, it must be easily transportable. Setting up an operation of the unit should also be simple.

Taking into account these criteria, it is proposed that a flexible system be established, as shown in Figure 2.

Water will be pumped directly from the river (without filtration and temperature control) by a portable gasoline engine driven pump. The tanks for the spawners receive their water supply direct from the pump, but a constant pressure water supply must be provided for the incubation and larval rearing equipment via an elevated head tank.

The outflow water from the various items of equipment will be collected in a drainage pipe of fairly large diameter placed just below ground level, and directed back to the river.

Most of the equipment needed for fish propagation can be installed in a 30 m2 light-structure building or a tent, but tanks for the spawners should be placed outdoors. The tanks used for keeping spawners will be aerated by an air blower via diffusers.

An electric generator is required to provide electricity for nighttime work and for the operation of instruments and some equipment. The air blower and the electric generator should be installed in a separate building or tent, where storage space and a room for staff can also be placed.

All components of the system are designed as flexibly connected portable units which can be installed and transported easily. The equipment required for the hatchery is listed in Appendix 2, and details of hatchery construction are shown in Figures 3, 4, 5, 6 and 7.

In the four 2.5 m3 tanks some 200 kg of spawners can be kept simultaneously. The eight 8–1 hatching jars have a total capacity of about 400 000 eggs (50 000 eggs/jar) while the three 200–1 larval rearing tanks are capable of holding all the newly hatched larvae from the eight jars. The 4 m3 head tank will store enough water to supply the hatching jars and the larval rearing tanks for about one hour in the event of pump failure.

2.3.2 Large-scale Hatchery

It is proposed that fertilized eggs will be transported from the on-site pilot hatchery to the large-scale hatchery, where facilities for the incubation of larger volumes of eggs are available.

The existing hatchery at the Fisheries Research Institute in Xining is used for the propagation of Chinese carps, and, in addition to the special spawning and incubation facilities, a 600 m2 greenhouse is also available for fish nursing.

In order to make this hatchery suitable for naked carp propagation the following major modifications are recommended:

It is recommended that the existing hatchery building be enlarged by 30 m2. A closed pressure filter unit with high filtering velocity and a capacity of 10–12 m3/h could be useful here. The technical specifications of a possible model are given in Figure 8. The filtered water could then be pumped into the existing head tank, where the temperature can be controlled if necessary.

The same type of hatching jars and larval rearing tanks can be used here as are specified above for the pilot scale hatchery. The installation of 32 hatching jars (into units comprising 16 jars each) and 12 larval rearing tanks are recommended. The estimated output capacity of the enlarged hatchery is 1.5–2.0 million larvae/cycle.

2.3.3 Nursery Ponds

The survival of larvae after release into the natural environment could be increased considerably by nursing them up to 3–4 cm size before they leave the hatchery. Nursing can therefore be expected to have a great effect on the success of any restocking programme.

Unfortunately there is no experience on the nursing of naked carp larvae. However, the consultant believes that conventional nursing ponds could be successfully used for this species.

At the Fisheries Research Institute at Xining there is a vacant area suitable for nursing pond construction. It would be possible to connect the new ponds to the existing water supply and drainage system. It is recommended, however, that the nursing ponds should not be built in the same way as the existing deep ponds.

Though the advantages of deep ponds have been proved in the warm climatic regions of China, in the cool climate of Qinghai Province shallow ponds may be advantageous since the water can warm up better in a pond where the average water depth is only about one metre.

No drainage canal is available at low level at this site, and the water must be pumped out of the ponds. Therefore nursing ponds should not be larger than 500 m2 in order to facilitate easy and safe harvesting. This size of pond can be conveniently harvested by fine mesh nets.

Since there is no outlet in the pond the bottom should have a slope of 0.1–0.2 percent towards the inlet. In such a pond fresh water could be provided for the concentrated fish stock during harvest. The proposed slope of the earthen dikes is 1:3 in order to provide more shallow water areas around the pond dike to promote the production of feed organisms.

Pipe inlets with a diameter of 150 mm and equipped with closing devices are recommended for the nursing ponds. It is important to filter water through a fine mesh before it flows into the ponds.

2.3.4 Transporting Equipment

In the proposed system the transportation of the fertilized eggs and the nursed fry is an essential part of the operation. A four-wheel drive truck with a maximum load capacity of 2 t would be sufficient. The eggs can be transported in the special polystyrene boxes used for the transport of live salmonid eggs.

The nursed fry can be transported either in oxygen filled plastic bags or in fibreglass tanks. Since there is no experience on the transportation of nursed naked carp fry, the best way of doing this must be worked out through experiments.


During the 1989 spawning season the water level of the Buha river was fairly high, and large groups of migrating naked carps could be observed.

It was also observed that the stream line, the shape and the sedimentation of some sections of the river have been altered considerably when compared with those conditions described in an article from 1965.

It was also learned that there are some general water management problems concerning the watershed management of those rivers flowing into Qinghai Lake. The flow rate of some of these rivers have been reduced considerably by human interventions, and partly as a result of these the water level of the Qinghai Lake is decreasing an average of 10 cm per year. Although there are plans to improve watershed management around the lake, their implementation has not started yet.

Since it was only possible to pay a very short visit to the Buha River, and detailed information was not available about plans for the improvement of watershed management, no detailed recommendations can be made here concerning the improvement of flow conditions in the Buha River.

However, taking into account the site and other conditions in the region, major technical interventions (construction of spurdikes, etc.) are not recommended. Instead, by studying existing maps and site surveys, shallow sections of the river where the free movement of migrating fish is hindered should be identified.

In these stretches the water depth should be increased by excavation. A dragline is recommended for this purpose.

Figure 1.

Figure 1. Qinghai lake and its surroundings

Figure 2.

Figure 2. General layout of the on-site pilot scale hatchery complex

Figure 3.

Figure 3. Layout of the hatchery

Figure 4.

Figure 4. Cross section of the hatchery

Figure 5.

Figure 5. Tank for spawners

Figure 6.

Figure 6. Details of the hatching jars

Figure 7.

Figure 7. Details of the larvae rearing tank

Figure 8.

Figure 8. Closed pressure filter

Appendix 1


Horváth, L. Jr., G. Tamás and A.G. Coche. 1985 Common carp. 1. Mass production of eggs and early fry. FAO Train. Ser., (8):87 (with colour filmstrip)

Horváth, L. Jr., G. Tamás and A.G. Coche. 1985 Common carp. 2. Mass production of advanced fry and fingerlings in ponds. FAO Train. Ser., (9):83 (with colour filmstrip)

Pagan-Font, F.A. and J. Zimet. 1979 Artificial propagation of Chinese carps. Filmstrip in colour and printed commentary. Rome, FAO, 270 photographs

Pagan-Font, F.A. and J. Zimet. 1980 Rearing fry and fingerlings of Chinese carps. Filmstrip in colour and printed commentary. Rome, FAO

Woynárovich, E. 1975 Elementary guide to fish culture in Nepal. Rome, FAO, 131 P.

Woynárovich, E. and L. Horváth. 1980 The artificial propagation of warmwater finfishes - a manual for extension. FAO Fish.Tech.Pap., (201):183

Anon. 1975 Fish distribution in Qinghai Lake and the biology of naked carp. Biological Institute of Qinghai, Scientific Publishing Company, Beijing (in Chinese)

Appendix 2


Gasoline engine driven water pump (2" suction and discharge ports, self priming, total head: 30 m, capacity 600 1/min) Type: Honda WA-20X or equivalent2 pieces
Gasoline engine driven electric generator
(220 V/50 Hz/1.3 kW)
Type: DENYO Model ACX-140 or equivalent
1 piece
Gasoline engine driven air blower
(capacity: 40 m3/hour, Head: 700 mm H2O)
Type: ELMO BH Ring Compressor No. 20310 or equivalent
2 pieces
2. *Tanks and Incubators
Head tank with level gauge and supports
(Volume: 4 m3, height: 3.0 m)
1 piece
Hatching jars with support and fittings
(8 litres)
8 pieces
Larvae rearing tanks with support and fittings (200 litres)3 pieces
Tank for spawners (2 m3)
Type AGK Model 03370 or equivalent
4 pieces
3. *Pipes and Fittings
Flexible pressure pipe (high pressure water supply pipe connected to the water pump) Æ 2"50 m
PVC Pressure pipe (high pressure water supply pipe) Æ 2" with threaded end connectors:
connectors30 m
90° bend3 pieces
T 2"1 piece
reducing T 2 × 2 × 1"5 pieces
flanged piece 2"2 pieces
PVC valve 2"1 piece
PVC pressure pipe (high pressure water supply pipe) Æ 1" with threaded end connectors:
connectors6 m
90° bend 1"4 pieces
PVC valve 1"5 pieces
PVC pipe light (low pressure water supply pipe connected to the head tank):
Æ 3" with threaded end connectors10 m
90° bend 3"2 pieces
T 3"1 piece
reducing T 3 × 3 × ½"12 pieces
flanged piece 3"1 piece
PVC valve 1/2"12 pieces
PVC pipe light (drainage pipe)
Æ 150 mm
60 m
PVC pressure pipe (air distribution pipe connected to the air blower):
Æ 32 mm extended with threaded end connectors10 m
reducing T 32 mm/20 mm4 pieces
PVC valve 20 mm4 pieces
Spiral hose (discharge pipe from the Zug jars and the larvae rearing tank):
Æ 63 mm int.6 m
Æ 30 mm int.20 m
plastic funnel Æ 200 mm4 pieces
PVC hose (air supply pipe for the spawner tank)
Æ 19 mm int.
20 m
Air distributor (with a hose connection of Æ 20 mm). Type AGK Model 20722 or equivalent4 pieces
Binocular microscope with Petri dish1 piece
Quick balance 200 g1 piece
Quick balance 10 kg1 piece
Dissolved oxygen meter1 piece
pH meter1 piece
Water thermometer3 pieces
5.Devices and tools for propagation and experiments
- fish manipulation table
- dipnet for spawners
- plastic bowls (3–4 l and 10–12 l)
- plastic buckets (15–20 l)
- glass measuring cylinders
- pipettes
- syringes
- medical scissors, scalpels, forceps, surgical needles with thread
- plastic tubings
- magnifying glasses
- oxygen bottles (for packing of larvae)
- plastic bags (for transport of larvae)
- plastic boxes (for transport of larvae)
- towels and cloths
- tool kit
Storage cabinet for chemicals and tools
Working table with chair
7.Electric Equipment
Main connection box with main fuse and main switch
Cables for power transmission and lighting
Outdoor lighting
(2 × 125 W mercury vapour lamp mounted on posts)
Internal lighting (8 × 120 W fluorescent lamps, 6 in the hatchery, 2 in the support unit)
Switches for lighting, plug sockets
Electric water heater

* It would be most advantageous if the tanks and incubators with the necessary pipes and fittings were supplied by one supplier as a package unit after preassembling and trial operation

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