Originally Posted by Gordo124
What toxic issue??
Nitrogenous waste excreted by fish respiration and defecation. Fish create ammonia which is toxic to them. In a cycled tank, this ammonia is converted into nitrite (which is also toxic) and then into nitrate (minimally toxic). This process is done by bacteria, but the bacteria take some time to colonize and become effective at converting the waste. So in really small newly setup or newly added to tanks it's a good idea to at least test regularly. I recommend doing water changes frequently since the fish isn't going to be in there long anyhow and it just makes sure that the water is in tip top shape.