I've always had a love of fish and have always had a tank. Recently I have changed from Cichlids to more unusual fish. We have 3 bala sharks, 2 pictus catfish, a eclipse catfish, a golden nugget pleco, a peacock eel and a bichir. All living happily in a 230 gallon tank. yesterday our eel started swimming like a crazy animal and hanging out upside down. ( we think swim bladder ) so we removed him from the tank and put him in our 35gl hospital tank we mainly use for growing plants and keeping new fish. He was dead by the morning. Unfortunately we weren't able to treat him last night. Everyone else seems to be fine. However when I check on the larger tank this morning and turned the light on, our bichir was dead on the bottom. No signs of trauma ( he was usually the one who killed and ate the other fish ) I checked the water again and everything seems to be normal. Nitrate and Nitrite are both 0-5 ppm, alkalinity is in 7's the only thing I didn't have time to do was test the ammonia. He ate fine last night and was swimming around and stalking his frozen shrimp. Its very strange. Any help on what may have caused this would be great cause I don't know if I can handle anymore loss of fish. I would like to replace both the eel and the bichir but would like to know what happened first.