Hi there, i have recently set up a new tank, and possibly lost two fish to "new tank syndrome". Basically I set the tank up a few week ago and let it sit for a while, its a standard sized 4ft aquarium. I am running an Aquis 1250 filter bull of bio media and filter floss, couple of power heads in there for circulation a bunch of rocks and a couple of texas holey rocks.
8 Days ago I added 6 small electric yellows, and started dosing the tank with Prime and Stability. I was under the impression that it would be safe to add some more fish. I added 5 red fin kadangos, 5 yellow tail blue acei and 1 synodontis petricola. Everything seemed fine, PH steady at 8.0, ammonia slowly climbed to 1.0ppm so I did a 50% water change, then yesterday the nitrates appeared and climber to about 20ppm while the ammonia stayed at 1.0ppm. So i did another 50% water change. No presence of nitrite at any point. Im testing all parameters every morning and night. All of the fish seemed fine. I had to remove 1 red fin kadango as he was incredibly aggressive. All of the kadangos are about 7 cm. 1 of the Acei is about 7 cm, the other 4 are about 4 cm and the yellows are all about 4 cm.
Today when I left for work they all seemed fine, but when I got home, two of the small acei were dead. Both of there lower jaws were missing, their fins were shredded and there were tiny chunks of flesh missing from both sides of them. All of the other seem perfectly normal, swimming around a lot, colouring up nicely and no damage to fins. Im just wondering if these 2 acei may have died due to injury from another fish, or from ammonia poisoning or something else. Currently Ammonia is at 1.0ppm, nitrite 0ppm, nitrate 10 or 20ppm, ph 8.0.
Thank you for your time.