Can i add freshwater tropical fish to a tank without treating the water first?
Three days isn’t long enough for a tank to go through the nitrogen cycle. There won’t be enough established bacteria in your filter media capable of supporting fish yet which will lead to an ammonia spike which can kill fish. Unless you’ve cloned the filter media from another tank of course. I would recommend water conditioner for any tank. Tap water contains chloramine (more so than chlorine these days) which does not evaporate and is designed to kill bacteria – which will directly impact on that established bacteria you desperately need for a tank to be healthy and be able to support fish. Conditioner will also remove other properties from the water, specifically heavy metals such as copper and zinc which would otherwise be harmful to those animals living in the tank.
