Odang Carman

Genetic Diversity of Boeseman's Rainbowfish (Melanotaenia Boesemani) Reared in Indonesian Farms Compared to Endangered Natural Populations

Endemic to two lakes (Ayamaru and Uter) of West Papua (Indonesia), the Boesemans Rainbowfish Melanotaenia boesemani Allen & Cross, 1980 is a very popular ornamental freshwater fish. As a result, this rainbowfish species faces great threats and is on the red list of endangered species. Therefore, rearing of this species in aquaculture systems appears to be a promising solution to limit capture of wild specimens and prevent its extinction. Although its reproduction cycle has been controlled for more than 30 years, very few farms still raise M. boesmani, probably due to the problems reported by the farmers, such as decline of production, higher proportion of females per spawning, loss of coloration, lower growth rate and fecundity. Using 12 microsatellites previously developed for this species, comparison of genotypes within six farms around Jakarta indicated that all reared strains originated from Ayamaru Lake. No deficit in heterozygotes was evidenced, suggesting that there was no major inbreeding in these reared populations. Genotype analysis also suggested that M. boesemani species is a metapopulation composed of genetically differentiated populations. Altogether, these results indicate that the problems experienced by the farmers are due not to inbreeding depression but to other factors such as inadequate management and/or poor water quality. Yet, increasing aquaculture production is probably the most effective way to alleviate the pressure that M. boesemani faces in its natural environment.

Development of twelve novel polymorphic microsatellite DNA markers for the Boeseman’s rainbowfish (Melanotaenia boesemani) and tests for their cross-utility in 21 rainbowfish species from West Papua (Indonesia)

We developed 12 microsatellite markers for the endangered Boeseman’s rainbowfish (Melanotaenia boesemani). Twenty-eight individuals from the type locality at Ayamaru Lake were examined, and all loci were polymorphic with a number of alleles per locus varying from 3 to 18. Average observed and expected heterozygosities were 0.681 and 0.678, respectively. Cross-species amplification was successfully obtained for 21 Melanotaenia species, with a number of alleles per locus ranging between 1 and 20. Average observed and expected heterozygosities varied between 0.105 and 0.708 and 0.118–0.755, respectively. Only 21 inbreeding coefficient (Fis) values presented a significant homozygote excess among the 264 locus-by-locus calculated values. Tests for genotyping errors revealed that four of these 21 significant Fis values could be explained by the presence of null alleles. These new microsatellite markers appear highly reliable for further conservation purposes or population genetic studies of the many rainbowfish endangered species.

GROWTH IN NURSERY AND GROW-OUT PHASES OF WHITE SHRIMP AFTER IMMERSED IN RECOMBINANT GIANT GROUPER GROWTH HORMONE

The growth of white shrimp ( Litopenaeus vannamei ) can be improved by using recombinant fish growth hormone through immersion. This research was performed to evaluate the white shrimp growth at nursery and grow-out phases after recombinant giant grouper growth hormone (rElGH) immersion. Shrimp were immersed at different stages in one liter seawater containing 15 mg rElGH for two hours. At the nursery stage 30,000 PL4 that previously immersed at nauplius stage (treatment A1), at PL4 (treatment B1) and control without rElGH immersion (K1) were reared in fiber tanks containing 750 L seawater for 8 days. At the grow-out phase, 1 00 PL11 that have been immersed in rElGH solution at nauplius stage (treatment A2), at PL4 (B2), PL11 (C2) and control without rElGH immersion (K2) were separately reared in fiber tanks containing 750 L seawater for 55 days. Each treatment consisted of three replications. The results showed that at the end of the nursery phase, B1 treatment increased 19% of body length, 30.2% of the body weight and decreased the coefficient of length variation 34.9% compared to control K1 (P<0.05). At the grow-out phase, C2 treatment enhanced 38.2% of body weight and 32% of biomass compared with control K2 (P<0.05). Thus, hatchery is better to immerse PL4, and the farmer should used rElGH-immersed PL11 for growing-out. Keywords : growth promoting, nursery, grow out , Litopenaeus vannamei , rElGH

A rapid chromosome preparation technique without metaphase arrest for ploidy determination in Nile tilapia, Oreochromis niloticus

Abstract Most chromosome preparation techniques use colchicine or colcemid in order to arrest cell division during metaphase, which usually involves the use of high cost materials. This research was aimed to simplify fish chromosome preparation technique without using colchicine or colcemid. Ten fish of different ages, namely one-, two- and three-month-old Nile tilapias, were used in this research. Tissues were collected on the caudal fin of the fish. Chromosome spreads was easily observed, using Giemsa or silver staining, five hours after the whole preparation process. The results showed that the one- and two-month-old fish had better mitotic index (0.008 and 0.01, respectively) compared to those of the three-month-old fish (0.005). This method is rapid, cost-efficient and applicable for ploidy level determination, and also keeps fish alive for subsequent evaluations.