thks all.... actually i failed to keep prata & any other kind of brians earlier..... all will die within short time of period...
however, when i got my new tank & without any fish inside the tank... i found that the brains are doing very well... but after i collected back all my fishes... then again, all brains did not open.... i monitor closely & found the culprit was 3 of my blue tang.... so, catch them out & now really can see the result... all brains open nicely.....