Genotype by Environment Interaction for Growth in Giant Gourami (Osphronemus goramy)

In the process of selection activities to obtain superior fish farming activities carried out through stages according to POS of rearing of such fish. The selection process is done by gradding of the fish population that is taking groups of fish with the best growth performance to a certain extent. Selection activities carried out in certain sizes and different for each species of fish, in addition to any consideration or breeders have different reasons in determining the size or age of the fish that will be selected. In general, the selection of breeders agree should be done on the consumption size. After getting selected fish with the desired character, then the labeling or "tagging" to facilitate the next process in the "breeding programe".

Giant gourami (Osphronemus goramy) has a growth pattern in which males have more rapid growth than females (Sularto et al., 2016). Therefore, we need a specific strategy in the framework of the selection process. Another thing to consider in the selection of giant gourami are environmental factors of cultivation. As reported by (Bangera et al., 2015) that in aquaculture, environmental variables such as photoperiod, temperature and production system may significantly influence growth performance of fish across production environments. Differences in the environmental variables may induce a phenomenon called genotype by environment interaction (G × E). Therefore, to reduce bias in the selection of giant gourami poses due to environmental factors, it is necessary to be carefully taken into account both factors.According to Bangera et al. (2015) that the genotype × environment can be separated into two forms: re-ranking and heterogeneity of variances. Re-ranking means that the rank order of genotypic performance change across different environments, i.e., the best genotypes in one production environment may not be the best in other production environments.

This study used four carp populations, namely: Jambi, Kalimantan, Majalengka and Tasikmalaya. Fourth populations were initially kept in the same container cultivation, then at the age of 11 months do rankings based on body weight. Having obtained several groups in each population then maintained in a separate pool, after the age of 15 months are tagged with a micro-chip and then kept in the same pool until the age of 25 months. Sampling fish growth was done once a month, while the water quality observations carried out every two months.

The results showed that at the age of 11 months were the best growth in the population Majalengka (384.28 ± 75.95), followed by Kalimantan population (370.01 ± 71.09), Tasikmalaya (341.54 ± 65.34), Jambi (315.29 ± 50.46). There were indications that the environment affects the growth of giant gourami and there are indications that it was not always a strain or an individual has always excelled in all environments Table 2). At 18 and 25 months there were no differences between strains. This was presumably because it has entered the phase of gonadal maturation.