Hi all - I “adopted” a group of fish from a friend about a week ago. Below is what I took from her: - 1 BN Pleco - 5 green lantern platys - 9 zebra danios (mix of long and short finned) - 3 dwarf honey gouramis I have them in a 20 gal quarantine tank and I’ve so far lost 1 gourami, 3 platys, and 2 danios. The tank has a filter I took from an established tank and should be cycled - established tank is cycled and the fish are thriving in that one. I’ve been testing the quarantine tank daily since I took the fish in and readings have been consistent: Ammonia: 0-.25 Nitrites: 0 Nitrates: 0 Since I have the established filter material in there shouldn’t I be seeing some Nitrates by now? It almost seems like it’s re-cycling... And is that .25 ammonia reading enough to blame the deaths on? The fish all appeared to be healthy when I took them, and in the case of the ones that have died I’ve noticed a very sharp decline in health - normal and swimming around at bedtime, then hanging out on the bottom of the tank (but still alive) in the morning, then dead within a few hours at most. I just want to do everything I can to keep the remainder alive but who knows what they may have been exposed to prior to me taking them. Edited to add: I also added a bottle of Safe Start to the tank before I took in the fish for good measure and have been using Prime as well.