So about 2-3 months ago I bought a 20 gal long tank and overpriced it with four goldfish, 2 black moors, a fancy and a fantail. I had terrible filtration and after doing reasearch realized I was slowly killing my fish via ammonia poisoning. Surely, one of my black moors died in the 20 gal before I could upgrade. About 7 weeks ago I moved the three remaining goldfish to a 35 gal long tank with two filters, a mainland penguin 350 & a tetra whisper 40i. In just four days my ammonia levels dropped and remained under .50 until last week where they dropped to 0. Since moving the fish the black moor has been hiding at the bottom of the tank except during feeding time. Last nigh he wedged himself in between the internal filter and glass, I thought he was dead until I moved the filter and he swam away rather lazy. This morning I found him in the same position except he was dead. Water (tested today) Ammonia - 0 Nitrate - 0 Nitrate - 0 Ph - between 7.8 - 8.0 Temperature around 60 - 65 degrees I guess im wondering if he kinda offend himself from depression or knew he was going to die and hid? Anybody have similar situations?