Who Gives A Fish Forums

I think you might want to try gradually lowering the temperature to around 80 degrees. Are you still getting any ammonia or nitrite readings? If so, you could consider adding Prime water conditioner, it's supposed to help minimize the harm from ammonia and nitrites. Has he shown any improvement with ...

I'm curious, what's the filter type you're using in your 9L tank. If it's a power filter, you might consider switching to a sponge filter, which is air-driven and has a much gentler flow. This could be a good solution given the small tank size and single fish.