from my experience, only the F1 and F2 from the imported stocks are showing the resonable quality, from F3, you need to introduce new bloodline to stengthen the pool. however, new indroduction can result 'kicking back'( not desiable tail type), and only small % fries are showing the quality, and worth to keep breeding.
two of the main probs we having are 1. limitation of quality stocks. 2. the way we keeping them.
back to basic. the original way of keeping fighters in Thai land is jaring or pond keeping, water change,and high protein live food. lets forget about filteration and fleaks etc, sometime, we are thinking too much on behalf of fighters, eg. bigger area for fighers to swim, Oxygen, water flowing etc. regarding to water quality, there is no way apart from manually water change can keep fighters happy.