The faster growth and higher survival of a strain, including the giant freshwater prawn (GFP), is an urgent requirement to support GFP farming. The selective breeding of GIMacro II (the superior strain of GFP) resulted in a fourth-generation (G4) which grew faster (35%) than the based population (G0). The comparative test among the selected GI Macro II (SGM), the control of GI Macro II (SGM), and the Siratu (SR, the previous superior strain) were conducted to evaluate the performance of these strains in the larval rearing phage, resistance to vibriosis of the larvae, and tolerance to stressors (pH, temperature, salinity, and formaldehyde) of the juvenile. In the larvae rearing stage, the growth (Larvae stage index, LSI) of the three populations was not different, there were 10.25 ± 0.14, 10.31 ± 0.18, and 10.12 ± 0.15 for SGM, CGM, and SR, respectively. The survival rate of the SGM is about 59.92 ± 4.631 %, significantly higher than the CGM larvae (52.67 ± 2.64 %) and SR larvae (45.85 ± 1.74 %). The resistance level of SGM larvae to Vibrio sp. infection (72.75 ± 4.88 %) is not different from the CGM larvae (70.25 ± 5.06%) and SR larvae (67.88 ± 6.59%). The tolerance level of the SGM, CGM, and SR juvenile to low pH, formaldehyde, temperature fluctuation, and salinity fluctuation were relatively high (>90%). The data suggested that the selected GI Macro II has a good prospect to be developed in the GFP farming system.

The decreasing productivity and increasing environmental pressure on intensive tilapia culture in open waters, especially in floating net cages, have forced the development of a biofloc system for tilapia farming. This study was aimed to develop the superior tilapia strain suitable for the biofloc system, their productivity and economic profitability under commercial scale in the biofloc system. The selective breeding activity was carried out on 100 families reared and mated in hapa in the biofloc pond for three generations. Individual selection was conducted at the age of 6 months on the characters of standard length and body weight with the best 10% reference for formation of the next generation. After three generations, the offspring obtained from mass spawning were grown out in round-limen ponds and square-concrete ponds for productivity and profitability observations. The results showed that heritability values ​​of the biofloc tilapia strain were 0.4196 (standard length, SL) and 0.4898 (body weight, BW). The average response selection of BW and SL were 13.04% and 6.11%, respectively. Biomass gain was obtained between 19.29–28.83 kg/m3. The production multiply value was 8.07-13.59x. The average daily weight growth was between 2.8g-3.0g. The Benefit-Cost ratio valued from 1.81 to 2.71.