I’ve got a disaster on my hands. I recently purchased 10 healthy discus from Discus Hans and they are all now dying. The fish were purchased for a new 150G tank setup and I did a fishless cycle before receiving the fish. No other fish have lived in the tank. I suspect I have a water problem, but am totally puzzled by it. First the equipment:
Tank: 150G (72”L x 18”W x 28”H)
Filters: 1.) Eheim 2217, 2.) Eheim 2028, 3.) Spongefilter on a powerhead
Heaters: 1.) Visitherm 300W submersible, 2. Hydor 300W ETH
(both heaters controlled by a Jehmco controller)
Temp is kept at 85 Fahrenheit
Substrate: Pool Filter Sand (was well rinsed, no cloudiness)
Decorations: A few rocks, Manzanita driftwood, plastic plants
Here's the Chronology
October 18: Started cycling my tank in a fishless cycle. Carefully monitored Ammonia, Nitrite and Nitrate. Tank was finally ready (Ammonia – 0, Nitrite – 0, Nitrate -10) at the beginning of December. I continued to dose with pure ammonia daily (bringing the level to 5ppm) until just before the fish arrived. Ammonia would always go to zero by the next day. The night before the fish arrived, I did a 75% water change.
12/19: Received 10 discus and 6 BN Plecos from Discus Hans. All discus larger than 3-inches, the BNs were just under 1-inch. After a day or so, all the discus were swimming well and eating. By the end of the first week, the discus would eat frozen bloodworms from my hand. I had no fish prior to this and have added none since.
From 12/19 until 1/14/09 everything was fine. All the discus appeared healthy and ate like pigs. I fed about four times daily – mostly FBW, but I would mix in some OmegaOne Flakes and TetraColor Tropical Granules. They far preferred the FBW (I used both Hikari and San Francisco). I performed 50% W/Cs twice weekly. Ammonia/Nitrite/Nitrate steady at 0ppm/0ppm/5ppm. PH measures 7.8 to 8.0.
1/14: The discus showed no interest in eating during my afternoon and evening feedings. The next morning, most of the FBW clump was sitting on the bottom uneaten by the next morning.
From that point onward, the fish just did not eat. I would feed and the food would sit. I started doing 50% W/Cs every other day.
1/19: First discus found dead (a Blue PB). It was looking sick the night before and was on the bottom in the morning. All the other fish looked good and were swimming normally. Still no eating. When I got home from work, I found a second dead discus (a Blue Snakeskin) and another Blue PB dying on the bottom. According to my wife, the PB was on the bottom most of the day and the Snakeskin stayed with it. Suddenly the Snakeskin started swimming rapidly about the tank and banging into the sides. It later settled into a plastic plant where it died.
Since 1/19, I have performed 50% W/Cs daily.
1/20: Came down in the morning to find the second Blue PB dead. The other fish were actually looking a bit better and swimming around more, rather than hiding in the corners.
1/21: Fish all looking poorly and hiding in corners again. In an attempt to remove possible contributing factors, I removed all driftwood and rocks and all but two of my plastic plants. Tests hold steady at 0/0/5 with PH at 7.8.
1/22: With morning I found a Red Scribbelt discus on the bottom near death and my other Blue SnakeSkin looking poorly. All fish hiding in the corner. Did my normal 50% W/C and vacuum. The Red Scribbelt died in the afternoon.
1/23: The Blue Snakeskin is dead. This makes a total of five dead discus out of the original ten.
I’m at a total loss to explain the cause. I’ve been in constant communications with Hans and he has been incredibly helpful - he even sent me some food!. I could not ask for better support than what he has provided. I am sure that I received healthy fish, but something in my water or setup is killing them. The fish show no outward signs of disease, except their color is a bit faded. Any suggestions?