My girlfriend bought a log decor at the store I put it in 2days ago and yesterday morning I found My Delhezi and saddled back bichirs dead. I did a 50% water change and this morning my ornate, senegal and weeksi bichirs were dead. So I did another 50% water change. I still have a ghost knife and african knife and pecastomus left that are doin fine. I test my water and do a 25% water change every week and have had these fish for years. what happened what should i do? thankyou anyone