I set up a ten gallon aquarium (no heater) with 2 small perch (tank raised) and a crayfish about three weeks ago. Since then, I’ve been topping the tank off once a week with treated tap water…I treat with an aquarium water conditioner and some Jungle StartRight (or some such product). I treat according to the labels on the packaging (they recommend using with each other).
So then on Friday, I vacuumed out the tank using a gravel vac, draining about 25% of the water. I topped the tank off with some treated tap water that had been sitting in a bucket for a few days (I filled it to let the water come to room temp with the plans to clean it that day, but ran out of time so I had to put it off until a few days later). After vacuuming, I pulled out the filter. I didn’t have a new one (I know you’re supposed to replace it, but I didn’t have a new one), so I rinsed it and put it back in.
After that, the fish stopped eating and started looking sluggish. On Monday morning, one of the fish was dead. Then, the other died tonight (Tuesday).
Any idea what I might be doing wrong? I was careful not to use any soap or anything like that during the cleaning process.