One of my bgk who is th biggest among the four died today around 4 1/2 inch, i just did a 50% WC after I changed the water I went to sleep, and then when I wake up today and about to go to work, I noticed the bigger bgk is laying on its side, I was about to poke him when he moved. I already knew that he was about to die coz he has been breathing heavily and how he swam was kind of abnormal.
I was thinking of the water quality coz the three other guys are still kind of stressed out (one is laying on its side but still fine). Then I remembered that the people that have been constructing the roads outside (or replacing the water pipes) of our house. I think after they changed the pipes (really big pipes) that caused the problem. I also noticed that the bgk that died has some blood on its tail (this I don't know what happend).
So those who have been keeping bgk, don't use tap water incase someone from the government agency has been reconstructing/replacing your water pipes around your area. Instead get water from one of your tanks.
Will post pics when I'm back home.