CAN THO UNIVERSITY
COLLEGE OF AQUACULTURE AND FISHERIES
STUDY ON SEED PRODUCTION OF
FIRE EEL (Mastacembelus erythrotaenia)
By
NGUYEN TAN DUY
A thesis submitted in partial fulfillment of the requirements for
the degree of Bachelor of Aquaculture Science
Supervisor
Dr. BUI MINH TAM
Can tho, December/2013
Approvement of supervisor
Approvement of student
Acknowledgements
I would like sincerely to thank the administrators of Can Tho university,
freshwater hatchery technicians and all teachers in college of aquaculture and fishery. I
would like sincerely to express gratefulness to my advisor Dr. Duong Thuy Yen who
has created the best condition and has taught precious knowledge for me during
studying at college.
I would like sincerely to thank Dr. Bui Minh Tam and M.Sc. Le Son Trang who
have helped and have transmitted guidance for me to finish this thesis. I would like
sincerely to thank my parents, relatives and my friends who have encouraged and
helped me during doing this thesis.
Thank sincerely!
i
Abstract
Fire eel is scarce and new fish species in Mekong river delta. The external shape
of fire eel is very beautiful and can be used for decoration. There are not many studies
on artificial propagation of this species and it is only exploited from nature, therefore
study on seed production of fire eel is implemented.
Research is implemented from june 28 to December 22 in 2013. The content of
research includes: (1) Stimulate artificial propagation of fire eel by combining HCG
and pituitary gland hormone and(2) Rearing larvae by different feeding regimes.
In research on artificial propagation of fire eel females were injected 4 times.
The first two injections were induced at 500 IU/kg of HCG, the interval between them
was 24 hours. After 24 hours the third dosage was induced at 1500 IU/kg of HCG
combined with 2 mg/kg of pituitary gland. After 10 hours, the final dosage was
induced at 4000 IU/kg of female. The result indicated that the response time was 15 to
16 hours, ovulation rate reached 100%, relative fecundity reached 8419 ± 244.21
eggs/kg, fertilized rate achieved 94.8 ± 3.59 %, hatching rate reached 52.88 ± 17.41 %,
time of embryo development was 58 to 60 hours, the interval of yolk sac’s completely
absorption was 12 days.
The larval rearing experiment was 35 days. Moina was fed to larvae till 5th, then
changed to tubifex worm. There are 4 treatments including (1) Tubifex worm was
completely fed to larvae in 35 days and treatment 2, 3, 4, tubifex worm was fed to
larvae till 15th, 20th, 25th then changed to home made feed. Result indicated that there
was significant difference (p<0.05) between treatments. Treatment 1 resulted in highest
growth rate and survival rate (final weight 0.98 ± 0.2 g, final length 6.454 ± 0.57 cm,
and survival rate 98 ± 2 %). Treatment 2 had lowest effective in term of growth rate
and survival rate (final weight 0.158 ± 0.078 g, final length 3.685 ± 0.5 cm, and
survival rate 78 ± 5.29 %). The result confirmed that tubifex worm is the best feed for
larval rearing, home made feed should be provided at higher days old of larvae.
ii
Table of Contents
Acknowledgements .............................................................................................................. i
Abstract ............................................................................................................................... ii
Table of contents ................................................................................................................ iii
List of figures ..................................................................................................................... vi
List of tables ..................................................................................................................... viii
List of abbreviations ........................................................................................................... ix
CHAPTER 1: INTRODUCTION ........................................................................................ 1
1.1 Research objective ..................................................................................................... 3
1.2 Research contents ...................................................................................................... 3
CHAPTER 2: LITERATURE REVIEW .............................................................................. 4
2.1 Scientific classification and morphology of fire eel .................................................... 4
2.1.1 Taxonomy ........................................................................................................... 4
2.1.2 Morphology ........................................................................................................ 4
2.2 Distribution ................................................................................................................ 5
2.3 Feeding ...................................................................................................................... 5
2.4 Environmental condition ............................................................................................ 6
2.5 Reproduction ............................................................................................................. 6
2.6 Reproductive Seasonality in fish ................................................................................ 6
2.7 Relationship between nutrient accumulation and development of gonad .................... 6
2.8 Scientific basis of fish reproduction stimulation ......................................................... 7
2.9 Hormone used in stimulating fish propagation ........................................................... 8
2.9.1 Using pituitary to stimulate artificial propagation ................................................ 8
2.9.2 Using HCG to stimulate artificial propagation ..................................................... 8
2.9.3 Using ovaprim to stimulate artificial propagation ................................................ 8
2.10 Researches in artificial propagation and larval rearing of Mastacembelidae family .. 8
3.1 Material ................................................................................................................... 12
3.1.1 Experimental site............................................................................................... 12
iii
3.1.2 Experimental time. ............................................................................................ 12
3.1.3 Equipment ......................................................................................................... 12
3.1.4 Chemical ........................................................................................................... 12
3.2 Research methodology ............................................................................................. 12
3.2.1 Stimulate maturation of broodstock ................................................................... 12
3.2.2 Stimulating artificial propagation of fire eel ...................................................... 14
3.2.2.4 Method for incubation .................................................................................... 18
3.2.3 Larval rearing experiment of fire eel ................................................................. 18
3.2.6 Data collection method ...................................................................................... 20
3.2.6.1 Data collection in broodstock conditioning ................................................. 20
3.2.6.2 Data collection in stimulating artificial propagation ................................... 21
3.2.6.2 Data collection in larval rearing .................................................................. 21
3.3 Data analysis ............................................................................................................ 22
CHAPTER 4: RESULT AND DISCUSSION .................................................................... 23
4.1. Environmental factors in broodstock conditioning .................................................. 23
4.1.1 Temperature ...................................................................................................... 23
4.1.2 pH ..................................................................................................................... 24
4.2 Stimulate artificial propagation by HCG and pituitary gland hormone ..................... 25
4.3 Embryo development of fire eel ............................................................................... 28
4.4 Larval rearing experiment ........................................................................................ 31
4.4.1 Environment factors in larval rearing experiment .............................................. 31
4.4.2 Growth rate in length of larvae .......................................................................... 32
4.4.3 Growth rate in weight of larvae ......................................................................... 35
4.4.5 Survival rate of larvae ....................................................................................... 37
CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS ....................................... 39
5.1 Conclusions ............................................................................................................. 39
5.2 Recommendation ..................................................................................................... 39
REFERENCES .................................................................................................................. 40
APPENDIX ....................................................................................................................... 42
iv
List of figure
List of figure
page
Figure 2.1: Morphology of male and female .............................................................. 4
Figure 2.2: Effect of ecological and physiological factor in natural reproduction ....... 7
Figure 3.1: Composite tank for broodstock conditioning .......................................... 13
Figure 3.2: PVC for hiding of fire eel ...................................................................... 13
Figure 3.3: Frozen shrimp is the main feed for broodstock ...................................... 14
Figure 3.4: Morphology of female’s genital hole ..................................................... 14
Figure 3.5: HCG and pituitary gland hormone ......................................................... 15
Figure 3.6: Inject female fire eel .............................................................................. 16
Figure 3.7: Stripping female’s egg ........................................................................... 17
Figure 3.8: Stripping male’s sperm into needles....................................................... 17
Figure 3.9: Artificially fertilizing fire eel’s egg ........................................................ 17
Figure 3.10: Spreading egg evenly out all the net ..................................................... 18
Figure 3.11: Net frame is flooded in water ............................................................... 18
Figure 3.12: Initial length at stocking of fire eel larvae ............................................ 19
Figure 3.13: Home made feed is pressed to pill before feeding ................................ 20
Figure 3.14: Setting up larval rearing experiment of fire eel .................................... 20
Figure 4.1: Temperature fluctuation in broodstock conditioning .............................. 24
Figure 4.2: pH fluctuation in broodstock conditioning ............................................. 25
Figure 4.3: The difference in color between fertilized and unfertilized egg .............. 27
Figure 4.4: Fungi the reason for low hatching rate ................................................... 27
v
Figure 4.5: External shape of fire eel larvae after yolk sac’s absorption ................... 28
Figure 4.6: Measuring length of newly hatch larvae of fire eel ................................. 29
Figure 4.7: Development of fire eel’s embryo .......................................................... 29
Figure 4.8: Mean final length of larvae in 4 treatments ............................................ 33
Figure 4.9: Relationship between day and length of larvae in control treatment ....... 34
Figure 4.10: Measuring final length after 35 days of rearing .................................... 34
Figure 4.11: Mean final weight of larvae in 4 treatments ......................................... 36
Figure 4.12: Relationship between day and weight of fish in control treatment ........ 37
Figure 4.13: Mean survival rate of larvae in 4 treatments ......................................... 38
vi
List of table
List of table
page
Table 3.1: Stimulating propagation by HCG and pituitary gland ...................................... 16
Table 3.2: Rearing larvae by different feeding regimes .................................................... 19
Table 4.1: Temperature in broodstock conditioning ......................................................... 23
Table 4.2: pH in broodstock conditioning ........................................................................ 24
Table 4.3: Reproduction indexes of fire eel after stimulating artificial propagation .......... 25
Table 4.4: Development of fire eel’s embryo ................................................................... 30
Table 4.5: Environment factors in larval rearing experiment ............................................ 31
Table 4.6: Growth rate in length of larvae ........................................................................ 32
Table 4.7: Growth rate in weight of larvae ...................................................................... 35
Table 4.8: Survival rate (%) of larvae .............................................................................. 37
vii
List of abbreviations
g
Gram
mm
Milimeter
cm
Centimeter
kg
Kilogram
HCG
Human chorionic gonadotropin
LHRH-A
Luteotropin hormone releasing hormone analog
FSH
Follicle stimulating hormone
LH
Luteinizing hormone
DA
Dopamine
IU
International unit
SD
Standard deviation
M
Morning
A
Afternoon
W
Weight
L
Length
viii
CHAPTER 1: INTRODUCTION
Aquaculture is more and more developing in the world. In Viet Nam aquaculture
is developing and has an important role in economics of the country bringing large
income for people and country. Seafood export earns 6,130,000,000 dollars in which
shrimp products earn 2,240,000,000 dollar, tra catfish products earn 1,700,000,000
dollars. Therefore, aquaculture has contributed 3.1-3.7% GDP, also according to
department of aquaculture in July 2012 production of capture and aquaculture reaches
531,300 ton in which fish products reach 379,200 ton and shrimp products reach
101,200,000 ton. Production of aquaculture in july 2012 reaches 344.200 ton in which
fish products reach 232,600 ton and shrimp products reach 91,800,000 ton. Water surface
area for aquaculture in 2012 reaches 1,059,000 ha and it is predicted that in 2013 water
surface area for aquaculture will reach 1,200,000 ha (Department of Aquaculture in
2012).
Mekong river delta is a key economic area in producing aquaculture and
agricultural products of Viet Nam. Aquaculture activities in Viet Nam are well developed
in Mekong river delta because this area accounts for a large production and water surface
area of the country. Areas for aquaculture in Mekong river delta is 709,980 ha, total
production for aquaculture reaches 1,014,590 tons accounting for 72% total aquaculture
production of country (Department of Aquaculture in 2012).
With complex river and canal systems and there are two seasons including flood
season and dry season each year, Mekong river delta creates good conditions for growth
of many fresh water fish species in which Tra Catfish is major export commodities of this
area. In 2012 tra catfish culture area reaches 5,910 ha, production reaches over 1,280,000
tons and export value reaches 1,740,000,000 dollars. However, recently there are
difficulties due to market price, so farmer tends to culture other different native species
that also have high economic value. In addition to demand about meaty fish, many
consumers are even interested in playing ornamental fish which they culture for
decoration. Therefore there is higher and higher requirement about ornamental fingerling
for export. Fire eel which has scientific name Mastacembelus erythrotaenia is a new
ornamental fish species. They are fresh water species and widely distribute in Southeast
Asia such as India, Malaysia, Myanmar, Sri lanka, Thailand, Indonesia, Cambodia, Lao,
and Viet Nam. Requirement about environment condition is not very strict with this
species because they can survive in temperature range 24-28 oC, pH 6.5-7.5, hardness 121
15 dH. In nature fire eel can reach 1.2 meters in length. Feed for fire eel is easy to find
such as prawn, brine shrimp, mussel, bloodworms and frozen foods.
Because of these reasons fire Eel is very suitable to be cultured in Mekong river
delta. Fire eel could be cultured for decoration in house because it is very beautiful
ornamental fish species. Moreover, it also has high economic value because in market
fire eel with sizes of 15-20 cm has price from 75,000-100,000 VND. However, there are
not much researches about this species especially in artificial reproduction techniques. In
addition, the demand of consumers for this species is higher and higher while the number
of fingerling is limited and only exploited from nature. Because of this reason, research
on seed production of Fire eel is conducted. The success of this research will contribute
in artificial propagation process of fire eel to meet the fingerling demand of consumers.
2
1.1 Research objective:
Study on seed production of this species needs to be conducted and applied to
recover these populations and meet demand of consumers. Immediately two main
objectives need to be reached including: (1) determine the total dosage of hormone and
the number of injection time to induce ovulation of fire eel, (2) determine the suitable
feeding regime for larval rearing.
1.2 Research contents:
1. Conditioning broodstock in capture conditions.
2. Stimulating artificial propagation of fire eel by HCG and pituitary gland.
3. Rearing larvae by different feeding regimes.
3
CHAPTER 2: LITERATURE REVIEW
2.1 Scientific classification and morphology of fire eel
2.1.1 Taxonomy
According to Truong Thu Khoa and Tran Thi Thu Huong (1993) fire eel belongs
to:
Kingdom: Animalia,
Phylum: chordate
Class: Actinopterygii
Order: Synbranchiformes
Family: Mastacembelidae,
Genus: Mastacembelus
Species: Mastacembelus erythrotaenia.
English name: fire eel
2.1.2 Morphology
Figure 2.1 a: Female fire eel
Figure 2.1 b: Male fire eel
Fire eel has small and flat head, snout is long and pointed as short beard in the
front side. Tooth is small and fine, small eye under skin slant to half over the head and
near the tip of snout. In front of eye there is one pointed thorn toward behind. Forehead
between two eyes is narrow, flat, nearly 1.5 times eye diameter, gill’s hole is small. The
4
body is long with pipe-shape, the belly is round and the tail part is quell. The scale is
small, fine, cover all body and a head part. Origin of dorsal fin is long, in front of dorsal
fin there is 31-32 thorn, final thorn is biggest and longest. The skin membrane between
thorns just presents at the origin. Behind, the soft ray is stick together by skin membrane
and thick muscle. Anus fin has three thorns, the first thorn is small and short, the second
thorn is big and long, the third thorn is in muscle. The soft rays have the same structure as
back fin. Starting point of back fin soft ray is horizontal with starting point of anus fin
soft ray. Pectoral fin is round and small, tail fin is very small and stick with anus fin and
dorsal fin. There is no abdomen fin(Truong Thu Khoa and Tran Thi Thu Huong, 1993).
Fish has color of gray-green or slightly black. There is red round small spots run
from the later head to the end of tail stalk. Upper and below these spots has 2-3 paleyellow stripes. The peak of dorsal fin, anus fin, caudal fin has yellow color and many
yellow round small spots. Origin of thorn of dorsal fin has red color. Origin of caudal fin
has one small black spot (Truong Thu Khoa and Tran Thi Thu Huong, 1993).
The fire eel can grow up to a very considerable size in the wild with specimens
often exceeding 1.2 meters (3.9 ft) in length. However, due to limiting factors in the
captive environment they usually reach a maximum of around 55 centimeters (22 in)
even in very large aquaria.
2.2 Distribution
Fire eel is widely distributed in south-east Asia such as India, Malaysia, Myanmar,
Sri Lanka, Thailand, Indonesia, Cambodia, Lao, Viet Nam. Fire eel inhabits usually
sluggish lowland waters including floodplains and slow current (Truong Thu Khoa and
Tran Thi Thu Huong, 1993).
2.3 Feeding
Fire eel is omnivorous but mainly carnivorous and consumes a variety of smaller
fish, aquatic invertebrates, plant matter and detritus. They prefer meaty foods such as
prawn, brine shrimp, krill, mussel, mosquito larvae, bloodworms, cyclops and lancefish.
Live and frozen foods can also be fed, however these foods alone are unlikely to be
enough to sustain larger fish. Some specimens will also accept vegetable matter, although
this is fairly rare. They are also bottom-feeder and predator that spend large portions of
their time buried in the riverbed and they are active in the night time. Fire eel often likes
hiding in rock and digging substrate such as gravel, sand to hide. Moreover, they also like
eating roots of floating plants and this aquatic plant can reduce light intensity that fire eel
does not want to expose. So in culture of fire eel rock, gravel, sand and floating plants
need to be provided.
5
2.4 Environmental condition
Fire eel is fresh water fish, the demand about water quality for growth of fire eel
is not very strict, the temperature range is about 24-28 0C, hardness is from 2-15 ppm, pH
range is from 6.5-7.5.
2.5 Reproduction
Fire eel lays egg only and egg will hatch after 3-4 days, Captive spawning is rare
and extremely difficult, even with mature fish over 20 inches (51 cm). Use a large tank
with a pH around 7.0, water hardness from 10–15 dH, and a temperature from 27–29 °C
(81–84 °F). Fish lays 800–1,200 eggs in aquatic plants. The eggs are clear and measured
around 1 millimeter (0.039 in) in size.
2.6 Reproductive Seasonality in fish
According to Pham Minh Thanh and Nguyen Van Kiem(2009) the development of
gonads undergos 6 stages, spawning of fish occurs when physiological and ecological
conditions are favorable for fish. When fish gets matured and meets suitable environment
conditions for development and existence of larvae and embryos, fish will reproduce. In
contrast, if fish gets matured but ecological and physiological conditions are not suitable,
fish will not reproduce. This indicates that environmental and ecological factors affect
maturation and gonad development of fish, but environmental and ecological factors are
affected by climate, weather and season. Therefore, there is close relation between each
period of year with each development stage of fish’s gonad.
Due to variation of environmental factors relates to seasonal climate change that
almost fish species in Mekong river delta have gonad in stage II in December and
January, stage III in February and March, stage IV in April and May. Therefore,
development of gonad following cycle is basis for aquaculturists construct plan for
culturing broodstock effectively, from here avoid culturing very early (loss cost) or very
lately.
2.7 Relationship between nutrient accumulation and development of gonad
According to Pham Minh Thanh and Nguyen Van Kiem (2009) in development of
gonad and ovary fish needs to be provided with enough nutrients. These nutrients one
part will be structure of body, the other part is accumulated in organizations as liver and
muscle in form of Lipid and Glycogen. They are also used to provide energy for activities
of daily life. Many researches indicated that reproductive cells grow up thanks to nutrient
metabolism from muscle and liver. This nutrient metabolism consumes energy and it is
provided by feed. Therefore, nutrient accumulation in fish is important basis for nutrient
metabolism into gonad gland.
6
According to Winberg (1968) cited by Pham Minh Thanh and Nguyen Van Kiem
(2009) diet in broodstock conditioning needs to be suitable and balanced. High or low
diet is not good for gonad development of broodstock, when increasing diet fecundity
will increase to a point and then stop and if continue to increase, fecundity decreases.
This is basis explaining why at the end of broodstock conditioning diet is reduced.
According Pham Minh Thanh and Nguyen Van Kiem (2009) nutrients which are
mobilized from muscle, liver to gonad gland are protein and lipid, this is basis for at the
end of broodstock conditioning protein and lipid content (%) are increased in diet.
2.8 Scientific basis of fish reproduction stimulation
There are two factors affecting to fish’s reproduction consist of ecological factor
and physiological factor (Pham Minh Thanh and Nguyen Van Kiem, 2009), ecological
factors are environmental conditions as flow, dissolved oxygen, rain while physiological
factors are hormones that affect directly or indirectly on fish’s gonad. Ecological factors
are necessary condition for creating physiological factors. However, decision for fish’s
reproduction is belong to physiological factors. One more another important condition for
fish’s reproduction is maturation of gonad. If ecological or physiological factors appear
but fish’s gonad doesn’t get matured reproduction does not occur, and on the contrary if
fish’s gonad is matured but ecological and physiological factors do not occur, fish’s
reproduction also does not occur. According to Pham Minh Thanh and Nguyen Van
Kiem (2009) if fish gets matured but fish could not be stimulated artificial reproduction,
ovary will be degenerated after 15-20 days, so it is basis for choosing the most suitable
period to stimulate artificial reproduction. The following diagram shows role and
mechanism of ecological and physiological factor in natural reproduction:
Ecological signals
Sensory organ
Central nervous
GnRH
DA
FSH
Environment
Gametes
Gonad
Pituitary
LH
Figure 2.2: Effect of ecological and physiological factor in natural reproduction
Base on the above diagram ecological signal will impact central nervous to secrete
GnRH and DA, GnRH will stimulate pituitary to secrete gonadotrophic as FSH and LH.
In contrast DA will inhibit pituitary from secreting gonadotrophic FSH and LH. FSH
7
hormone stimulates yolk sac formulation and LH stimulates ripe and ovulation (Pham
Minh Thanh and Nguyen Van Kiem, 2009).
2.9 Hormone used in stimulating fish propagation
2.9.1 Using pituitary to stimulate artificial propagation
Pituitary gland is used firstly in 1930 in artificial propagation experiment. Pituitary
gland contains a large number of 2 hormones as FSH and LH that have direct impact on
gonad gland and to stimulate yolk sac formulation and cause ripe and ovulation (Pham
Minh Thanh and Nguyen Van Kiem, 2009).
2.9.2 Using HCG to stimulate artificial propagation
HCG usually called Human Chorionic Gonadotropin Hormone or placenta
hormone, it has function like LH hormone that has direct impact on gonad gland and
cause ripe and ovulation. HCG is used firstly to stimulate artificial propagation in 1936
by Morozoa (Pham Minh Thanh and Nguyen Van Kiem, 2009).
2.9.3 Using ovaprim to stimulate artificial propagation
Ovaprim is a mixture of 20 ug sGnRH-A and 10 mg Domperidon in 1 ml
propylene glycol, ovaprim has indirect effect on gonad of fish, ovaprim stimulates
pituitary to secrete internal gonadotropin including FSH and LH while HCG and pituitary
hormone have direct effect on gonad of fish by providing external gonadotropin such as
FSH and LH.
2.10 Researches in artificial propagation and larval rearing of Mastacembelidae
family
In Viet Nam there has been the first research about artificial propagation of fire eel
in Aquaculture Research Institute 2 coordinated with national center for freshwater
fisheries seed of southern. The result indicated that broodstock with average weight over
100 g was cultured for maturation in cement tank, and was fed on frozen shrimp and
fresh death shrimp, feeding rate was 3-5 % body weight. After culturing 4-5 months they
got matured and ready for spawning. HCG was used in this research to stimulate
propagation of fire eel and the result indicated that eggs ovulated after 10 hours injection
at the temperature of 28-30 oC, ovulation rate reached 50 %. At the temperature of 26-28
o
C after 64 hours egg hatched. This result provides basis information for the next
researches, it shows that HCG has strong effect on propagation performance of fire eel.
Because fire eel is very new species, so research results about fish species that have the
same family or genus could be referenced.
8
Another research was also conducted at freshwater hatchery belonging to college
of aquaculture and fisheries in Can Tho University. In this experiment two hormone
pituitary gland and LHRH-a + Dom were combined to stimulate artificial propagation in
Macrognathus aculeatus. The preliminary dosage was pituitary with dosage of 0.3 mg/kg
female, the final or the resolving dosage was LHRH-a + Dom with dosage of 200 ug
LHRH-a + 10 mg Dom /kg female. The male was not injected, the interval between two
injections was 8 hours, the response time was 10-12 hours. The result indicated that
relative fecundity reached 26,700-37,800 eggs/kg female, fertilized rate reached 94 %,
hatching rate reached 37.9%, the hatching time was 38-42 hours, the interval of yolk
sac’s absorption was 3 days. In larval rearing experiment, zooplankton was fed to larvae
in the first 2 days, then changed to moina till day 9 th. Tubifex worm was fed to larvae
from day 9th till day 40th. Result indicated that daily weight gain reached 0.077 g/day,
daily length gain reached 0.213 cm/day, survival rate achieved 10.7% (Huynh Nha Trang,
2006).
Experiment stimulating artificial propagation in Macrognathus siamensis Gunther,
1861 was conducted by Duong Tran Trung Kien (2007) in Can Tho. Experiment was
designed with 3 different dosages of HCG such as 1500, 2000, and 2500 IU/kg female.
The result indicated that the ovulation rate was 86-100%, the response time was 6 hours
to 8 hours 40 minutes, the relative fecundity was 49,049 to 68,742 eggs/kg female,
fertilized rate was 58 to 69 %, hatching rate reached 49 to 56 %, hatching time reached
34 to 40 hours, the interval of yolk sac’s absorption was 3 days. Dosage 1500 IU/kg
female was the most effective one in which the relative fecundity reached 53,029 to
68,742 eggs/kg female, fertilized rate reached 62 to 69 %, hatching rate was 52-56 %.
In research conducted by Nguyen Quoc Dat (2007) HCG was used to stimulate
artificial propagation in Macrognathus siamensis, there were three dosages of HCG
corresponding to 1500, 2000, and 2500 IU/kg of female, female was injected 2 times, the
interval between two injection times was 10 hours, the preliminary dosage was 1/3 of
total dosage, and the resolve dosage was 2/3 of total dosage. The result showed that
ovulation rate was 100% in 3 treatments, the response time was 10h-10h30, fertilized rate
reached from 77.80-83.93 % and reached highest in treatment 1500 IU with 83.93 %. The
hatching rate achieved from 55.3-56.4 % but there was no significant difference (p>0.05)
in hatching rate, the result indicated that treatment 1500 IU was the most effective
dosage. In larval rearing experiment egg yolk was fed to larvae in the first 3 days then
changed to moina till day 8th. Tubifex worm was fed to larvae from day 9th till day 30th.
Result indicated that final length reached 46.52-57.21 mm, final weight achieved 0.480.86 g, survival rate reached 56.57-96.97 %.
9
The research on artificial propagation of Mastacembelus favus was conducted at
freshwater hatchery belonging to college of aquaculture and fisheries in Can Tho, there
were two experiments with three replications each treatment. In the first experiment there
were three treatments corresponding with three different injection times at 2,3 and 4
injection time to compare about ovulation rate and relative fecundity among treatments.
Fish was injected 500 IU/kg of HCG at preliminary dosage, and at resolving dosage fish
at three treatments was injected at 2000 IU/kg of HCG. In the second experiment there
were three treatments corresponding with 3 different dosages of HCG as 1000 IU/kg
female, 2000 IU/kg female, and 3000 IU/kg female which were in resolve injection, the
number of injection times was resulted from experiment 1. The result indicated that in
experiment 1 there was significant difference (p<0.05) among different injection times,
third injection time was seen to have highest effect in which ovulation rate reached
100%, relative fecundity reached 21,189 eggs/kg female. In experiment 2 there was no
significant difference (p>0.05) among treatments, the ovulation rate of all treatments
reached 100 % and relative fecundity, fertilized rate were not significant different among
treatments. However, treatment injected at 3000 IU/kg female was the most effective one
because time was shortest, hatching rate was highest with 73 % (Ngo Thi Kieu Ngan,
2008).
In other research on artificial propagation of Mastacembelus favus, female was
injected three times, in the first two injection times female was injected at 500 IU/kg of
HCG, the interval between the first two injection times was 24 hours, after 12 hours from
the second dosage female was injected the resolving dosage at 3000 IU/kg of HCG, 4
mg/kg of pituitary gland, 0.5 ml/kg of ovaprim. The result indicated that ovulation rate
had significant difference (p<0.05), the ovulation rate in treatment using HCG and
Ovaprim was 50 % that was lower than treatment using pituitary gland with 100% of
ovulation rate, the response time was shortest in treatment using pituitary at 4 hours 13
minutes. The relative fecundity was significant different (p<0.05) among 3 treatments
(p<0.05), relative fecundity in treatment using HCG was highest with 10,196 eggs/kg
female, next was treatment using pituitary gland with 7,443 eggs/kg female, and the
lowest fecundity was belong to treatment 3 with 3,474 eggs/kg female. Fertilized rate had
significant difference (p<0.05) among 3 treatments, fertilized rate in treatment 1 was
highest with 38.12 %, in treatment 2 was 18.12 %, and in treatment 3 was 0 % (Tran
Hoang Diem, 2009). Base on the above result HCG and pituitary were seen to have
higher effect than Ovaprim on reproduction performance.
Research on artificial propagation of Mastacembelus favus was conducted in
national seed center of southern. Broodstock was collected from nature in two provinces
10
- Xem thêm -