Untitled

Abstract

Sex control in aquaculture aims to benefit from desirable traits expressed differentially by each sex. In ornamental fish, such manipulation can be profitable, especially in species with high price discrepancy between sexes. This is particularly true for the fancy males of Siamese fighting fish (Betta splendens Regan, 1910), which are very popular aquarium pets. Therefore, fry originating from controlled reproduction were fed initially with artemia nauplii from day 4 post-hatch up to day 7 post-hatch. Subsequently, they were orally administered with 17a-methyltestosterone (MT) (via inert feed) in four concentrations (1, 2, 3, and 4 mg/kg of hormone in feed) for eight weeks. The experiment was repeated with fry of the same origin in identical conditions with the exception of a prolonged supply period (from day 4 post-hatch until day 11 post-hatch) of artemia nauplii enriched with red pepper. The results demonstrated that the 3 and 4 mg/kg doses resulted in 100% masculinization and the extended provision period of enriched artemia nauplii increased the survival rate of the offspring. However, mortality rate increased in all hormone treated groups in both experiments, partly due to the prolonged hormone administration period. Therefore, oral administration of low MT doses is effective for the masculinization of Siamese fighting fish.

Effects of synthetic androgen (17α-methyltestosterone) and estrogen (17β-estradiol) on growth and skin coloration in emperor red cichlid, Aulonocara nyassae (Actinopterygii: Cichliformes: Cichlidae)

“…The optimum 17α-MT supplementation rate for masculinization was reported to be 60 mg • kg -1 in O. niloticus (see Das et al 2010;Greisy and Gamal 2012), O. andersoni (see As et al 2012), and Poecilia reticulata (see Chakraborty et al 2012). Moreover, Phelps and Okoko (2011) observed the highest male rate (99.3%) in 30 mg • kg -1 MT supplemented fish group in O. niloticus and Kipouros et al (2011) obtained 100% males in groups supplemented with 2, 3, and 4 mg • kg -1 17α-MT. On the contrary, 17α-MT supplementation did not cause any significant difference in rosy barb and dwarf gourami (Ramee et al 2020), as well as in C. carpio (see Basavaraju et al 2008).…”

Sex Reversal in Siamese Fighting Fish Larvae by Thermal Management

“…Among the conditions for the success of the activity, prioritizing the production of male Betta splendens individuals is extremely important, given their accentuated development of the fins and more vibrant colors compared with females, attaining higher market values (Thongprajukaew et al, 2014). To increase the number of males from a single spawning, sex reversal techniques involving the use of hormones have been investigated in the species (Kavumpurath and Pandian, 1994;Kirankumar and Pandian, 2002;Kipouros et al, 2011;Reis et al, 2016).…”