1. EFFICACY OF COMMON CARP Cyprinus carpio TESTIS ENDUCING SEX REVERSAL OF NILE TILAPIA Oreochromis niloticus
Rahul Ranjan, Narayan P. Pandit*, Nabin B. Khanal, Madhav K. Shrestha, and James S. Diana
Department of Aquaculture and Fisheries
Agriculture and Forestry University, Nepal

2. Introduction
Sex reversal of Nile tilapia (Oreochromis niloticus) using 17α-methyl testosterone (MT) is the most commonly used method.
There is concern about the residual effect of MT on human health and environment.
It is not easily available and more costly in developing countries.
There is a need of exploring alternative natural androgen sources.
Use of animal testis as a source of natural androgen might be an alternative.

3. Testis is a good source of androgen.
- Bull testis (Phelps et al., 1996), hog testis (Mayer et al., 2008), and ram testis (Haylor and Pascual, 1991)
Fish testis is more suitable for sex reversal in tilapia
Common carp (Cyprinus carpio)
Early maturation
Higher gonadosomatic index
Two seasons of maturity
Easily available
Less costly than synthetic
hormone
Common carp testis (CCT)

4. Objectives
To assess the effectiveness of common carp testis (CCT) feeding on sex reversal of Nile tilapia.
To assess the optimum feeding dose of CCT for maximum sex reversal in Nile tilapia.
To find optimum feeding duration of CCT for maximum rate of sex reversal in Nile tilapia.

5. Materials and Methods
8-dah (days after hatching) mixed-sex Nile tilapia (GIFT strain) were used

6. Experimental setup and design
Six levels of CCT diets were prepared.
0 % CCT with fish meal
50 % CCT with fish meal
65 % CCT with fish meal
80 % CCT with fish meal
95 % CCT with fish meal
100% CCT with fish meal
Fed for three different durations (25, 30 and 35 days)
Experimental design- RCBD
Treatment duration- block
Feed types- factors

7. 60 fry in each aquarium (1.5 ft x 1.0 ft x 1.5 ft)
90% water replaced in each 2 days
Feeding (Twice a day; am and 3-4 pm)
20% initial week
Reduced 2.5% each week till 5%
Quantity fixed on basis of sampled fish
After treatment, fish were transferred to nylon hapa and reared until 160 dah with normal feed.
Feed type allocated randomly to each aquarium
Least survival- Aq fry
I-1, 12, 17
II- 3, 8, 13
III- 2, 7, 15
IV- 4, 5, 11
V- 6, 9, 18
VI- 10, 14, 16

8. Feed preparation Collection of Common carp testes (CCT)
Sun dried for 1-3 days
Dried testes crushed into pieces and grinded
Fine particles sieved
Mixed in required amount with fish meal powder
Testes stage- Mature and spermiating
Fresh CCT for drying

9. Dried CCT
CCT Powder

10. Feeding- 5% of body weight with 28% CP feed Fortnightly sampling
Post treatment phase
After treatment, fry were transferred to nylon happa (50 cm x 50 cm x 100 cm) and reared until 160 dah
Feeding- 5% of body weight with 28% CP feed
Fortnightly sampling
50% water changed weekly
Feeding in hapa

11. Sex differentiation Gonad observation All fish taken out Dissected
Gonad observed
Determined with naked eyes
Confirmed using staining material
Acetocaramine (0.5 g caramine in 100 mL of 45% acetone)

12. Results and Discussion
Sex reversal
Sex reversal towards male was based on dose dependent manner
Figure: Average male population with different doses of CCT

13. Treatment duration (days)
Table: Effect of CCT dosage and treatment duration on proportion of male of Nile tilapia (Mean±SE).
Feed type (CCT%)
Treatment duration (days)
Mean 25 30 35
0 (Control)
50.0±0.0
54.2±4.2
52.8±1.4c 50
62.5±7.2
75.4±4.0
66.8±4.3b 65
68.8±3.6
75.0±7.2
72.6±8.3
72.1±1.8b 80
69.6±10.9
79.2±4.2
70.4±4.8b 95
83.3±4.2
91.7±4.2
90.5±4.8
88.5±2.6a
100
87.5±0.0
95.8±4.2
93.1±2.8a
Mean (Excluding Control)
72.9±5.3a
78.9±6.4a
82.7±4.5a
Mean values with different superscript letters within column and within row are significantly different (p<0.05)

14. Gonadal structure Female Male Female gonad under 100x

15. Testis
Ovary

16. Growth during treatment phase
Figure: Growth trend of fish during sex reversal phase (35 days)

17. Table 7: Growth parameters of fry during treatment phase after 35 days
Treatment (CCT %)
Survival (%)
DWG (mg/fish/day)
SGR (%/day)
0 (Control)
90.00±4.41a
6.33±0.31c
8.55±0.14c 50
60.00±14.81b
11.93±0.78ab
10.29±0.19ab 65
57.78±10.18b
10.50±0.60b
9.94±0.16b 80
62.78±13.47b
10.98±1.55b
10.01±0.43b 95
65.00±13.64b
14.43±0.43a
10.83±0.08a
100
61.67±7.64b
11.57±1.14ab
10.19±0.27ab
Mean values with different superscript letters within column and within row are significantly different (p<0.05)

18. Higher dietary protein Increased amount of hormone in diet
Growth difference may be due to higher crude protein in CCT compared to fish meal.
Higher dietary protein
Increased amount of hormone in diet
Lower density
Asad et al. (2010)- protein level effect
Davis et al. (2010)- hormone level effect (11KT)

19. Water quality during treatment phase
Figure 13: Min- Max temperature and DO in aquarium during sex reversal phase

20. Figure 14: pH in aquarium during sex reversal phase

21. Conclusion
100% CCT fed for days produce significantly higher (95.83±7.22%) male population.
Male population increased with increased CCT dose
Increased male population with increased treatment duration

22. Recommendations for further study
Study on androgens present in CCT.
Development of processing method.
Histological, Immunohistological and steroid hormone profile of sex changed fish.
Develop a methodology for extracting hormone from testis.

23. Funding for this research was provided by the
The AquaFish Innovation Lab is supported in part by United States Agency for International Development (USAID) Cooperative Agreement No. EPP-A and by contributions from participating institutions.
This presentation is made possible by the generous support of the American people through the United States Agency for International Development (USAID). The contents are the responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government. Mention of trade names or commercial products in this presentation does not constitute endorsement or recommendation for use on the part of USAID or AquaFish. The accuracy, reliability, and originality of the work presented are the responsibility of the individual authors.

24. Thank You