Jurnal Akuakultur Indonesia 24 .
, 274Ae287 .
Original article DOI: 10.
19027/jai.
Induction of maturation gonads the Asian swamp eel Monopterus albus at different sizes with the hormones PMSG antidopamine and hCG Induksi maturasi gonad belut sawah Monopterus albus pada ukuran yang berbeda dengan hormon PMSG antidopamine dan hCG Aan Aryanti Sandra1.
Agus Oman Sudrajat2*.
Harton Arfah2.
Dinar Tri Soelistyowati2 Aquaculture Science.
Post Graduate Study Program.
Faculty of Fishery and Marine Sciences.
IPB University.
Bogor.
West Java 16680.
Indonesia Department of Aquaculture.
Faculty of Fisheries and Marine Science.
IPB University.
Bogor.
West Java 16680.
Indonesia *Corresponding author: agusom@apps.
(Received April 4, 2024.
Revised June 18, 2024.
Accepted March 4, 2.
ABSTRACT Monopterus albus is a protogynous hermaphrodite species that undergoes a unidirectional sex change from female to male.
Asian swamp eel cultivation activities face constraints in seeding due to limited mature gonad broodstock.
This study aims to evaluate the effect of administering a combination of PMSG Antidopamine (OodeveN) and hCG on the induction of gonad maturation of Asian swamp eels at various body sizes.
The research design used was a factorial design consisting of control treatment .
ithout hormone injectio.
P1 = hCG .
ose 20 IU/k.
P2 = OodeveN .
5 ml/k.
, and P3 = hCG OodeveN .
ose 20 IU 0.
5 ml/k.
with body length groups, namely K1 .
Ae25 c.
K2 .
Ae40 c.
, and K3 .
Ae55 c.
The results showed that eels in group K1 had the highest body length growth .
63 A 0.
96 c.
, while the highest body weight gain .
30 A 1.
30 gram.
in K3 (P<0.
Administration of oodeveN showed the highest values for GSI = 8.
13 A 0.
72% and HSI = 4.
36 A 0.
80% in K1 compared to K2 (GSI = 6.
95 A 2.
HSI = 3.
26 A 0.
68%) with female sex.
In contrast, group K3 experienced a decrease in GSI = 0.
81 A 0.
11% and HSI = 2.
48 A 1.
06% accompanied by masculinization.
Administration of oodeveN also increased the concentration of estradiol-17 in K1 and K2, while testosterone increased in K3.
The conclusion of this study is that administering oodeveN to 15-40 cm sized Asian swamp eels can accelerate gonad maturity with female sex status, while at sizes >45 cm it can accelerate masculinization and maturation of male Keywords: body length size, gonad maturation, masculinization.
Monopterus albus, oodeveN
ABSTRAK
Monopterus albus adalah spesies hermaprodit protogini yang mengalami perubahan jenis kelamin dari betina ke jantan secara searah.
Kegiatan budidaya belut sawah menghadapi kendala dalam pembenihan karena keterbatasan induk matang gonad.
Penelitian ini bertujuan untuk mengevaluasi pengaruh pemberian kombinasi PMSG Antidopamine (OodeveN) dan hCG terhadap induksi pematangan gonad belut sawah pada berbagai ukuran tubuh.
Desain penelitian yang digunakan adalah rancangan faktorial yang terdiri dari perlakuan kontrol .
anpa injeksi hormo.
P1 = hCG .
osis 20 IU/k.
P2 = OodeveN .
osis 0,5 ml/k.
, dan P3 = hCG OodeveN .
osis 20 IU 0,5 ml/k.
dengan kelompok ukuran panjang tubuh yaitu K1 .
Ae25 c.
K2 .
Ae40 c.
, dan K3 .
Ae55 c.
Hasil penelitian menunjukkan bahwa belut kelompok K1 memiliki pertumbuhan panjang tubuh tertinggi .
,63 A 0,96 c.
, sementara pertambahan bobot tubuh tertinggi .
,30 A 1,30 gra.
pada K3 (P<0,.
Pemberian oodeveN menunjukkan nilai tertinggi untuk GSI = 8,13 A 0,72% dan HSI = 4,36 A 0,80% pada K1 dibandingkan dengan K2 (GSI = 6,95 A 2,86%.
HSI = 3,26 A 0,68%) dengan jenis kelamin betina.
Sebaliknya, kelompok K3 mengalami penurunan nilai GSI = 0,81 A 0,11% dan HSI = 2,48 A 1,06% disertai dengan maskulinisasi.
Pemberian oodeveN juga meningkatkan konsentrasi estradiol-17 pada K1 dan K2, sedangkan testosterone meningkat pada K3.
Kesimpulan penelitian ini adalah pemberian oodeveN pada belut sawah ukuran 15-40 cm dapat mempercepat kematangan gonad dengan status kelamin betina sedangkan pada ukuran >45 cm dapat mempercepat maskulinisasi dan pematangan gonad jantan.
Kata kunci: maskulinisasi.
Monopterus albus, oodeveN, pematangan gonad, ukuran panjang tubuh Aan Aryanti Sandra et al.
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INTRODUCTION The Asian swamp eel (Monopterus albu.
is widely distributed across Asia, including the Indo-Malayan Archipelago.
Japan.
Asian Russia.
Burma.
China, and northern India (Supiwong et , 2.
Monopterus albus is one of the highvalue fish species in the Chinese seafood market (Newton et al.
, 2.
, making it a potential export For instance.
IndonesiaAos fishery export volume to China reached 428,056 tons, with an average annual growth rate of 9.
65% from 2016 to 2021 (KKP, 2.
In 2022, the export volume of M.
albus reached 8,197,296 kg with a free on board (FOB) value of 13,473,820 USD (BPS, 2.
Moreover, demand for M.
continues to rise, while domestic production remains limited, resulting in local market prices of live eels reaching IDR 70,000 per kilogram (Diatin et al.
, 2.
Due to its high economic potential.
albus has become an important aquaculture commodity.
However, one of the major challenges in its cultivation is the limited availability of sexually mature broodstock.
Monopterus albus is a protogynous hermaphroditic fish species, undergoing sex reversal from female to male through an intersex stage during its life cycle (Cai et al.
, 2.
Previous studies have shown that sex reversal in M.
albus is associated with body length and weight (Chen et al.
, 2.
, and may be influenced by both environmental and genetic factors (Feng et al.
, 2.
The sequence of sex differentiation in M.
albus is femaleIeintersexIemale, with body lengths O47 cm corresponding to the female stage, 47Ae55 cm to the intersex stage, and Ou55 cm to the male stage (Chen et al.
, 2.
In addition, endogenous steroid hormones such as estrogen and androgen play crucial roles in gonadal estrogen is involved in ovarian differentiation and maintenance, while androgen is associated with testicular maintenance (Li et , 2.
Fish reproductive regulation is a complex process influenced by multiple factors, including environmental, social, neural, endocrine, and metabolic cues (Gabilondo et al.
, 2.
One of the key mechanisms involved in gonadal maturation is the synthesis of gonadotropin-releasing hormone (GnRH) in the hypothalamus, which regulates the secretion of two pituitary gonadotropins folliclestimulating hormone (FSH) and luteinizing hormone (LH).
These hormones stimulate gonadal development and the secretion of sex steroid hormones (Zohar et al.
, 2010.
Biran & Levavi-Sivan, 2.
One of the hormones that can be used to stimulate gonadal maturation in fish is pregnant mare serum gonadotropin (PMSG) combined with an antidopaminergic agent (AD), as well as human chorionic gonadotropin .
CG).
PMSG has a higher follicle-stimulating hormone (FSH) content relative to luteinizing hormone (LH), making it more effective in accelerating gonadal maturation in fish (Mellisa et al.
, 2.
The antidopaminergic agent (AD) functions by blocking the dopaminergic inhibitory system to enhance GnRH secretion (Zohar et al.
, 2.
In addition to PMSG AD, hCG can also be used in the gonadal maturation process.
As a gonadotropin, hCG plays a significant role in fish reproduction by stimulating gonadal maturation and triggering ovulation and spawning (Elakkanai et al.
, 2015.
Murugananthkumar et al.
, 2017.
Kucharczyk et al.
, 2.
hCG acts directly on the gonads .
varies and teste.
, and thus its effects may be more rapid due to its direct induction at the gonadal level, stimulating the synthesis and release of sex steroid hormones, which in turn play a key role in gonadal maturation, spermiation, and ovulation (Saleh et al.
, 2.
Research on hormonal reproductive manipulation in Monopterus albus, particularly in relation to body length, remains limited.
Therefore, this study aims to evaluate the effects of PMSG AD (OodeveN) and hCG combinations on the induction of gonadal maturation in Asian swamp eels across various body size categories.
MATERIALS AND METHODS
Materials and experimental subjects The hormones used in this study were Pregnant Mare Serum Gonadotropin (PMSG) Antidopaminergic agent (AD), marketed under the trade name OodeveN, and human Chorionic Gonadotropin .
CG), marketed under the trade name PregnyleN.
The experimental subjects were Asian swamp eels (Monopterus albu.
categorized into three size groups: 15Ae25 cm, 30Ae40 cm, and 45Ae55 cm, with 60 individuals per size group.
These eels were wild-caught from rice fields in Kerinci Regency using traditional bamboo traps locally known as bubu, posong, or lukah .
n the Kerinci languag.
Experimental design The study employed a factorial design with two tested factors: hormone treatment and eel Aan Aryanti Sandra et al.
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size group.
The hormone treatments consisted of control .
o hormone injectio.
, treatment P1.
CG at a dose of 20 IU/k.
, treatment P2 (PMSG AD (OodeveN) at a dose of 0.
5 mL/k.
, treatment P3 .
CG OodeveN at a combined dose of 20 IU 0.
5 mL/k.
The size groups were K1 .
emale, 15Ae25 c.
K2 .
emale, 30Ae40 c.
K3 .
ntersex, 45Ae55 c.
, based on the classification by Chen et al.
Preparation of rearing media and experimental The rearing tanks used in this study were made of wood lined with plastic tarpaulin, each measuring 120y80y40 cmA.
Tanks were thoroughly cleaned with water and filled with 5Ae15 cm of water, followed by continuous aeration.
Environmental enrichment was provided using shredded raffia string and bamboo.
Oxytetracycline (OTC) was applied to the water at a concentration of 0.
g/L.
The water temperature during the study ranged from 22.
66 to 22.
90AC.
Prior to hormone injection, the eels were anesthetized using ArowanaeN brand stabilizer at a dosage of 1 mL/L for three minutes.
Hormone administration was performed via intramuscular injection according to the specified treatment Injections were administered every 10 days over a 70-day study period, for a total of seven injections.
Throughout the study, eels were fed daily during both the acclimatization and experimental phases .
orning, afternoon, and evenin.
with Tubifex worms at 3% of their body Water in the rearing tanks was replaced as needed when water quality declined .
due to turbidity or organic buildu.
Study parameters Body weight gain Body weight was measured before the initial hormone injection and every 10 days prior to each subsequent injection.
Measurements were taken using a digital scale with a precision of 0.
1 g.
Final body weight gain was calculated at the end of the study using the following formula.
Note:
BWG
= Body weight gain .
= Final body weight after the rearing period .
= Initial body weight before the rearing period .
Body length gain Total body length of the Asian swamp eels was measured at the beginning and end of the study using a 100 cm measuring ruler.
Body length gain was calculated using the formula.
Note:
BLG
= Body length gain .
= Final body length .
= Initial body length .
Gonadosomatic index (GSI) The gonadosomatic index was assessed on day 0 and at the end of the study on day 70.
GSI was calculated using the formula adapted from Ghaedi et al.
as it shown below.
Note:
GSI
GwAU = Gonadosomatic index (%) = Gonad weight .
= Body weight .
Hepatosomatic index (HSI) The hepatosomatic index was measured at the beginning .
and end of the study .
, and calculated following Wang et al.
by using the formula below.
Note:
HSI
BwAU = Hepatosomatic Index (%) = Liver weight .
= Body weight .
Survival rate (SR) The survival rate of the Asian swamp eels was calculated at the end of the experiment.
Survival Rate (SR) was determined using the formula from Yu et al.
Note:
NiAU = Survival Rate (%) = Final number of surviving eels = Initial number of eels Aan Aryanti Sandra et al.
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Sex identification Sex identification in Asian swamp eels was determined through morphological observations including body length, head shape, abdominal coloration, tail morphology, and the presence and coloration of gametes in the gonads.
All experimental subjects were classified into three sex categories: female, intersex, and male (Chen et al.
, 2.
Sex identification was conducted at both the beginning and the end of the study (Day Gonadal histology Gonadal histology was examined to evaluate structural differences in the gonads of eels subjected to various hormonal treatments across different size groups.
Observations were made descriptively, focusing on the histological structures of gonadal tissue, including oogonia, nucleus, yolk granules, yolk, degraded oocytes, spermatogonia, spermatocytes, spermatids, and Gonadal histology was observed at the end of the experiment (Day .
The histological assessment aimed to determine the stage of gonadal development, with all samples categorized into three developmental stages:
female, intersex, and male.
The histological procedure followed the method described by Gunarso .
, with tissue staining performed using hematoxylin and eosin (H&E) staining.
Estradiol and testosterone hormone analysis The concentrations of estradiol and testosterone in the blood plasma were measured on Day 40 and Day 70 of the study.
Hormone quantification was conducted using the enzymelinked immunosorbent assay (ELISA) method with the VIDAS ELISA kit.
RESULTS AND DISCUSSION
Results Body weight and length gain This study analyzed the effects of hormonal treatments and size groupings on the body weight and length gain of Asian swamp eels (Monopterus albu.
over a 70-day rearing period.
The results of the analysis are presented graphically in Figures 1 and 2.
Body weight gain showed no significant differences across all factors (P>0.
(Figure 1a, b, .
Body length gain did not differ significantly among treatment groups (P>0.
, but showed a significant difference among size groups (P<0.
, and no significant interaction effect was observed (P>0.
(Figure 2a, b, .
Based on the observations, both body weight and length gain Figure 1.
Body weight gain of Asian swamp eel (Monopterus albu.
over a 70-day rearing period.
effect of hormonal treatment.
effect of size group.
interaction effect.
P1 = hCG treatment.
P2 = PMSG AD or OodeveN treatment.
P3 = hCG OodeveN combination treatment.
K1 = size group 15Ae25 cm.
K2 = size group 30Ae40 cm.
K3 = size group 45Ae55 cm.
Different superscripts above the bars within each factor indicate statistically significant differences (P<0.
*All eels died, data excluded from statistical analysis.
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parameters were lower in hormonally treated eels compared to the control group.
Gonadosomatic index (GSI) Administration of PMSG AD (OodeveN) for 70 days was effective in increasing the gonadosomatic index (GSI) in Asian swamp eels of size groups K1 and K2 with female sex.
However, a decrease in GSI was observed in size group K3, which exhibited male sex characteristics (Figure .
Based on observations of the gonadosomatic index, the highest values for each factor were recorded Figure 2.
Body length gain of Asian swamp eel (Monopterus albu.
over a 70-day rearing period.
effect of hormonal treatment.
effect of size group.
interaction effect.
P1 = hCG treatment.
P2 = PMSG AD or OodeveN treatment.
P3 = hCG OodeveN combination treatment.
K1 = size group 15Ae25 cm.
K2 = size group 30Ae40 cm.
K3 = size group 45Ae55 cm.
Different superscript above the bars within each factor indicate statistically significant differences (P<0.
*All eels died, data excluded from statistical analysis.
Figure 3.
Gonadosomatic index (GSI) of Asian swamp eel (Monopterus albu.
over a 70-day rearing period.
effect of hormonal treatment.
effect of size group.
interaction effect.
P1 = hCG treatment.
P2 = PMSG AD
or OodeveN treatment.
P3 = hCG OodeveN combination treatment.
K1 = size group 15Ae25 cm.
K2 = size group 30Ae40 cm.
K3 = size group 45Ae55 cm.
Different superscript above the bars within each factor indicate statistically significant differences (P<0.
*All eels died, data excluded from statistical analysis.
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as follows: treatment factor P2 (PMSG AD or OodeveN) at 5.
29 A 3.
85%, size group factor K1 at 67 A 2.
65%, and the interaction factor (P2 y K.
13 A 0.
However, in size group K3, all treatments showed a decrease in gonadosomatic index (GSI).
Statistical analysis using ANOVA revealed significant differences in the hormone injection factor, size group factor, and their interaction (P<0.
Hepatosomatic index (HSI) Observation of the hepatosomatic index parameter showed that administration of PMSG AD (OodeveN) for 70 days increased HSI values in Asian swamp eels of size groups K1 and K2 .
emale se.
, while all treatments in size group K3 .
ale se.
exhibited decreased HSI values (Figure .
The highest HSI values recorded for each factor were: treatment factor P2 37 A 1.
10%, size group factor K1 at 3.
08%, and interaction factor (P2 y K.
However, in size group K3, all treatments showed a decline in hepatosomatic index (HSI).
Statistical analysis using ANOVA showed that the hepatosomatic index values differed significantly across hormone injection factors, size group factors, and their interaction (P<0.
Sex status The results of the sex status parameter for Asian swamp eel after 70 days of maintenance, analyzed descriptively, showed that Asian swamp eels in groups K1 and K2 remained female under all Meanwhile, group K3 treated with P2 and P3 experienced sex reversal from the intersex stage to male.
The sex status and characteristics of female, intersex, and male Asian swamp eels after hormonal induction on day 70 of rearing can be seen in Figures 5 and 6.
Gonadal histology The histological observations of the gonads of Asian swamp eels (Monopterus albu.
over a 70day maintenance period are presented in Figure The histological analysis showed that in the control treatment groups K1 and K2, oogonia .
and nuclei (N) were still present.
In treatment P1 groups K1 and K2, yolk (Y) and yolk granules (YG) had begun to appear, although nuclei (N) and oogonia .
were still present.
Treatment P2 (PMSG AD or OodeveN) showed that the gonads of groups K1 and K2 were filled with yolk (Y), indicating that administration of PMSG AD (OodeveN) effectively induced gonadal maturation in Asian swamp eels of groups K1 and K2, resulting in female differentiation.
In contrast, in group K3 .
Ae55 c.
, sex reversal from intersex to male Figure 4.
Hepatosomatic index (HSI) values of Asian swamp eel (Monopterus albu.
over 70 days of rearing.
treatment factor.
size group factor.
interaction factor.
P1 .
CG).
P2 (PMSG AD or OodeveN).
CG OodeveN).
K1 .
ize 15Ae25 c.
K2 .
ize 30Ae40 c.
K3 .
ize 45Ae55 c.
Different superscript above each bar indicate significant differences (P<0.
*All eels died, data excluded from statistical analysis.
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Figure 5.
Sex differentiation status of Asian swamp eels (Monopterus albu.
induced hormonally, visually or descriptively observed on day 70 based on body morphology.
female, .
intersex, .
kk = small head, kt = blunt head, kb = large head, p = white, pk = whitish-yellow, kkc = yellowish-brown, er = pointed tail, et = blunt Figure 6.
Sex differentiation status of Asian swamp eels (Monopterus albu.
hormonally induced and observed descriptively on day 70 based on gonadal morphology and histology.
female, .
intersex, .
male, y = yolk.
DO = degraded oocyte, t = testis.
Figure 7.
Histological development of gonads in Asian swamp field eels induced by hormonal treatments.
(Contro.
P1 .
CG treatmen.
P2 (PMSG AD or OodeveN).
P3 .
CG OodeveN).
K1 (Group .
K2 (Group .
K3 (Group .
OG .
N .
YG .
olk granule.
Y .
DO .
egraded oocyt.
SPG .
SPC .
SPT .
SPZ .
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was observed in treatments P2 and P3, evidenced by the absence of oocytes in the degradation stage (DO) and the presence of male germ cells such as spermatocytes (SPC), spermatids (SPT), and spermatozoa (SPZ).
However, in the control and P1 treatments of group K3, the gonads remained at the intersex stage, as indicated by the continued presence of degenerating oocytes (DO).
Estradiol-17 (E.
and testosterone (T) hormone Descriptive observations revealed that the concentrations of estradiol-17 (E.
and testosterone (T) in the blood differed significantly between female and male groups of Asian swamp Estradiol-17 levels were higher in Group K1 and K2 .
redominantly femal.
compared to Group K3 .
redominantly mal.
As shown in Figure 8, the highest concentration of estradiol17 was recorded in eels treated with P2 in Group K2 on day 40, reaching 0.
79 ng/mL, followed by a decline to 0.
57 ng/mL by day 70.
In contrast.
Group K1 showed a continuous increase in estradiol-17 levels, peaking at 0.
68 ng/mL on Meanwhile, testosterone levels in the larger-sized eels of Group K3 increased over the maintenance period, with the highest value observed in the P3 treatment group on day 70, 82 ng/mL.
Survival rate The survival rate (SR) of Asian swamp eels was assessed at the end of the study using a nonfactorial design.
The SR parameter over the 70day rearing period is presented in percentage (%) in Figure 9.
Based on Figure 9, the survival rate was observed to be lower in eels treated with P3 .
CG OodeveN) and P1 .
nly hCG) compared to the control and P2 (OodeveN) treatments.
Statistical analysis using ANOVA revealed a significant difference (P<0.
among the treatments.
Figure 8.
Graph of estradiol-17 and testosterone hormone levels in Asian swamp eels.
K = control.
P1 = hCG.
P2 = PMSG AD or OodeveN.
P3 = hCG OodeveN.
K1 = Group 1.
K2 = Group 2.
K3 = Group 3.
*All eels died, data excluded from statistical analysis.
Figure 9.
Survival rate graph of Asian swamp eel (Monopterus albu.
during 70 days of rearing.
Treatment, .
Size groups.
K1 = size 15Ae25 cm.
K2 = size 30Ae40 cm.
K3 = size 45Ae55 cm.
P1 = hCG.
P2 = PMSG AD or OodeveN.
P3 = hCG OodeveN.
Different superscripts above the bars within each factor indicate significant differences (P<0.
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Discussion The results of the study on weight and length increment parameters showed that Asian swamp eels (Monopterus albu.
subjected to hormonal treatments exhibited lower growth performance compared to the control group.
This is likely attributed to the absence of injection-induced stress in the control group, allowing them to efficiently allocate dietary energy toward maintenance and somatic growth.
Energy, defined as the chemical bonds in consumed feed, is released through oxidative reactions (Smith.
During catabolic processes, the chemical energy from food is transformed, with 40Ae50% being captured in high-energy compounds such as adenosine triphosphate (ATP), while the remaining energy is lost as heat (Zonneveld et al.
Amin .
reported that during gonadal development in European eel (Anguilla anguill.
, the ovary and testis utilized 25.
08% and 20.
of total energy intake, respectively.
Fish growth tends to decline during gonadal development due to the reallocation of energy toward gonad production (Lugert et al.
, 2.
Consequently, in Monopterus albus, gonadal maturation can inhibit somatic growth.
The gonadosomatic index (GSI) is a critical parameter reflecting reproductive development in fish and serves as an indicator of gonadal maturity (Kaur et al.
, 2.
The GSI provides a reliable measure of gonadal development for a given species under analysis (Flores et al.
, 2.
The present study demonstrated the highest GSI values in female eels from size groups K1 and K2, which received treatment P2 (PMSG AD or OodeveN), with values reaching 8.
13% and 95% respectively after 70 days of rearing.
ANOVA statistical analysis revealed significant differences in treatment, body size group, and their interaction (P<0.
These findings indicate that the administration of pregnant mare serum gonadotropin (PMSG) and antidopamine (AD) effectively stimulated vitellogenesis and gonadal development in Monopterus albus.
The use of PMSG AD (OodeveN) to accelerate gonadal maturation has also been successfully applied to other fish species, including Channa striata .
Osteochilus hasselti .
ilem car.
Poropuntius tawarensis .
awan fis.
, and Rasbora lateristriata .
ellow rasbor.
(Anwar et al.
, 2018.
Fitriatin et al.
, 2018.
Mellisa et , 2022.
Rey et al.
, 2.
A rapid increase in GSI typically signals the onset of vitellogenesis (Freitas et al.
, 2.
Conversely, in intersex and male eels, a decline in GSI was observed.
This decline is attributed to the degeneration of oocytes and the progression toward testicular development (Chen et al.
, 2.
These findings are consistent with the current study, where a reduction in GSI was observed in intersex and male eels from size group K3 by day 70 of the rearing period.
The gonadosomatic index (GSI) and hepatosomatic index (HSI) are commonly used indicators of gonadal development, energy allocation for reproduction, gonadal maturation, and spawning processes (Hismayasari et al.
, 2015.
Saleh & Ali, 2.
The findings of this study showed that the HSI value progressively increased in female Asian swamp eels (Monopterus albu.
in groups K1 and K2 receiving treatment P2 throughout the experimental period.
The highest average HSI values were recorded at 4.
36% for group K1 and 3.
26% for group K2 after 70 days of rearing.
An increase in HSI typically occurs when the ovary enters the vitellogenic phase, suggesting that vitellogenin production in the liver leads to increased liver mass, which subsequently elevates the HSI value (Pham & Nguyen, 2019.
Kumar et al.
, 2.
During vitellogenic growth, oocytes accumulate vitellogenin a yolk precursor protein rich in phospholipids synthesized by the liver and transported via the bloodstream to the The oocytes uptake and convert it into yolk reserves.
Upon completion of vitellogenesis, the ovary becomes filled with oocytes ready to undergo final maturation and ovulation (Reading et al.
, 2.
Nissling et al.
noted that peak HSI values in female fish occur just before spawning, which correlates with intensified feeding activity, as observed in Baltic flounder.
Likewise, the increase in HSI during ovarian maturation supports the liverAos enhanced role in vitellogenin synthesis essential for oocyte development (Freitas et al.
, 2.
In contrast, a decline in HSI is typically observed in male fish as they reach reproductive maturity (Freitas et al.
, 2.
In the present study, male Asian swamp eels from group K3 treated with P2 and P3 showed a decrease in HSI values on day 70, recorded at 48% and 2.
01%, respectively.
These results were statistically validated via ANOVA, which revealed significant differences among treatment groups, body size groups, and their interaction (P<0.
The descriptive analysis of sex status over the 70-day rearing period revealed that eels in groups K1 and K2 remained female across all treatments.
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In contrast, group K3 exhibited sex reversal from intersex to male under treatments P2 and P3 during the same period.
Prior studies have indicated that sex reversal in Monopterus albus is influenced by body length or weight (Chen et al.
, 2.
and environmental factors (Feng et al.
, 2.
Additionally, endogenous steroid hormones play a critical role in sex differentiation (Li et al.
The mechanisms underlying sex reversal in this species are complex and likely influenced by a combination of genetic, environmental, nutritional, and hormonal factors (Feng et al.
Li et al.
, 2019.
Jiang et al.
, 2.
This study found that the administration of PMSG AD (OodeveN) and hCG OodeveN hormones accelerated the transition from intersex to male in Monopterus albus over a 70-day period.
Although the precise mechanism of PMSG AD in inducing sex reversal remains unclear, it is hypothesized that the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) components of PMSG, combined with the dopaminergic inhibition effect of AD, stimulate gonadotropin-releasing hormone (GnRH) secretion, contributing to the observed sex reversal.
Several studies have reported that exogenous gonadotropin (FSH and LH) administration can induce sex changes in protogynous hermaphroditic fish species such as the orange-spotted grouper (Epinephelus coioide.
, tiger grouper (Epinephelus fuscoguttatu.
, and Asian swamp eel (Monopterus albu.
(Tang et al.
Huang et al.
, 2019.
Palma et al.
, 2019.
et al.
, 2.
Casas & Saborido-Rey .
reported that the hypothalamic-pituitary-gonadal (HPG) axis, also known as the endocrine axis, is the main signaling pathway that regulates sex change in hermaphroditic fish.
The hypothalamus releases gonadotropin-releasing hormone (GnRH) in the brain, which stimulates the pituitary gland to synthesize and secrete gonadotropin hormones (GtH.
, namely follicle-stimulating hormone (FSH) and luteinizing hormone (LH) (Zohar et , 2.
FSH plays a key role in regulating .
, whereas LH is involved in controlling testicular maturation .
(Mylonas et al.
, 2.
In this study, estradiol-17 (E.
and testosterone (T) levels in the blood were found to vary significantly among female, intersex, and male Asian swamp eels (Monopterus albu.
Results indicated that in group K2 females treated with P2 (PMSG AD or OodeveN), estradiol-17 levels increased on day 40 to 0.
ng/ml but declined to 0.
57 ng/ml by day 70.
Conversely, females in group K1 exhibited a continuous increase, peaking at 0.
68 ng/ml on day In group K3, testosterone levels increased in intersex eels and peaked in males under treatment P3, reaching 0.
82 ng/ml on day 70 of rearing.
These patterns suggest that estradiol-17 levels rise during the female phase, while testosterone levels elevate during the intersex and male phases.
Serum estradiol-17 levels significantly increase first during the female stage and then decline markedly during the sex reversal process in M.
albus (Chen et al.
, 2.
Hwang et al.
also observed high estradiol-17 concentrations in Japanese eel (Anguilla japonic.
females during the previtellogenic or early vitellogenic phases.
general, estradiol-17 levels in many fish species increase during vitellogenesis and decline after reaching full maturation (Moreira et al.
, 2015.
Ghosh et al.
, 2016.
Pham & Nguyen, 2019.
Mushirobira et al.
, 2.
This study demonstrates that administration of PMSG AD (OodeveN) elicited different hormonal responses across body size groups: groups K1 and K2 showed elevated estradiol-17 levels, while group K3 exhibited increased testosterone levels.
The rise in estradiol-17 levels in K1 and K2 females is likely attributed to enhanced aromatase enzyme activity induced by PMSG AD injections.
Watanabe et al.
stated that PMSG significantly increases the activity of P-450arom.
Cytochrome P-450 aromatase (P-450aro.
, encoded by the cyp19a1 gene, is the enzyme that catalyzes the conversion of testosterone into estradiol-17 and plays a critical role in gonadal differentiation and development (Watanabe et al.
, 1999.
Zhang et al.
However, the mechanism by which PMSG AD increases testosterone in intersex and male eels of group K3 .
Ae55 c.
remains unclear.
This phenomenon may be linked to the ongoing sex reversal process in Monopterus albus, in which FSH and LH contained in pregnant mare serum gonadotropin (PMSG) play pivotal roles in sex During the transitional stage from intersex to male.
albus exhibits a significant increase in 11-ketotestosterone concentrations (Chen et al.
, 2.
Furthermore.
Meng et al.
reported that testosterone levels in fully masculinized M.
albus are significantly higher than in females.
The histological analysis of Asian swamp eel (Monopterus albu.
gonads showed the Aan Aryanti Sandra et al.
/ Jurnal Akuakultur Indonesia 24 .
, 274Ae287 .
most favorable results in treatment group P2 (PMSG AD or OodeveN) for size groups K1 and K2.
In these groups, gonads treated with P2 were fully filled with yolk, indicating advanced vitellogenesis.
This confirms that PMSG AD (OodeveN) enhances the vitellogenesis process, leading to gonadal maturation in K1 and K2 groups.
Gonadal maturation in fish is characterized by enlarged ovaries that increase in weight and change color to yellowish due to yolk accumulation.
The mature stage is further marked by high yolk granule density, thickening of the zona radiata, and a decreased nucleus-tocytoplasm ratio (Esmaeili et al.
, 2.
Histological results in group K3 under treatment P2 indicated sex reversal from intersex to male.
Fan et al.
reported that intersex Asian swamp eels contain numerous male germ cells, including spermatogonia and spermatocytes, alongside a few early-stage or degenerating oocytes .
egraded oocyte.
In contrast, mature male eels are characterized by testes filled with spermatids and spermatozoa (Chakraborty, 2.
The study also found that survival rates were lower in treatment groups P3 and P1 compared to the control and P2 groups.
This reduction in survival is likely due to paradoxical effects associated with suboptimal hormone dosage or duration.
Hunter & Donaldson .
noted that excessive hormone dosages can induce paradoxical phenomena, leading to increased mortality, reduced growth rates, and even sterility in fish.
Other studies have confirmed that administering gonadotropin-releasing hormone (GnRH) in combination with LH can result in paradoxical effects in both mammalian and fish ovarian follicles (Habibi & Andreu-Vieyra.
Tsafriri, 2.
The paradoxical effect of gonadotropin hormones has been observed in many species, including humans, and has puzzled researchers for decades (Fallah & Habibi, 2.
This study confirmed that the effects of hCG.
PMSG AD (OodeveN), and hCG OodeveN vary depending on body size.
hCG injection in K1 and K2 eels promoted vitellogenesis but did not achieve full gonadal maturation.
In K3, no sex reversal occurred during the 70-day maintenance Meanwhile.
PMSG AD (OodeveN) injection in K1 and K2 successfully stimulated vitellogenesis to full gonadal maturity, while in K3 it induced sex reversal from intersex to male by day 70.
However, hCG OodeveN injection in K1 and K2 caused mortality after 40 days of maintenance, whereas in K3, sex reversal occurred by day 70.
Overall, the findings indicate that the most effective treatment was PMSG AD (OodeveN), yielding optimal outcomes in groups K1 .
Ae25 c.
K2 .
Ae40 c.
, and K3 .
Ae55 c.
over a 70-day maintenance period.
CONCLUSION
The administration of PMSG AD (OodeveN) at a dose of 0.
5 ml/kg in Asian swamp eels (Monopterus albu.
with a body length ranging from 15Ae40 cm can accelerate gonadal maturation in individuals with a female sex status, whereas in eels with a body length >45 cm, it can promote masculinization and gonadal maturation in males.
ACKNOWLEDGMENT
The authors are very grateful to the Center for Education Financial (Pusat Layanan Pembiayaan Pendidika.
and Indonesia Endowment Funds for Education (Lembaga Pengelola Dana Pendidika.
through Indonesian Education Scholarships (BPI ID: 202101100.
The authors would like to acknowledge Instalasi Pendung Semurup Kerinci (IPSK) and SKIPM (Stasiun Karantina Ikan.
Pengendalian Mutu dan Keamanan Hasil Perikana.
Jambi for facilitating this study.
REFERENCES