How long do you wait before you put a freshwater fish in your aquarium?

After you fill the tank with water, your supposed to wait a day or two. It may also say how long to wait in the directions that come with the tank.

Well it all depends on whether or not you are going to do a fish or a fishless cycle. A tank sitting by itself does nothing but settle. It doesn’t cycle unless there is a source of ammonia. I prefer fishless cycling. Search for fishless cycle and you’ll get a lot of good tips about cycling it. Most tanks can cycle in about 3 weeks regardless of size.

After the tank is completely set up: filters working, heater on, gravel and plants in place, etc.etc., I’d wait a week.

70 gallon aquarium, I will wait at least 72 hours before put in any fish.
Make sure run the thermostat and water filter within this waiting period.

If you are going to cycle the tank with fish, or are moving a working filter from an established tank, then you only need to wait for the water to settle and the temp to stabilise, 24 hours maybe. And thats optional, you could add fish right away and it woudn’t make much difference. But if the heater is not adjusted right you may have a problem.

But remember the tank is NOT cycled at this point, unless you move in a cycled filter. If the whole setup is new then you must still cycle the tank before it can support fish properly. This process may take 2 to 6 weeks depending on how you do it.

If you are going to cycle with fish, just add a couple of small hardy ones and keep a close watch on the water parameters for the first few weeks. Build up the fish numbers slowly to avoid a fatal ammonia buildup.

If you want to cycle the tank without fish, have a read of the link below, it explains how to do it. That will take maybe 3 weeks before the tank is ready for fish, but it’s no risk to your fish as you get the cycle working before you get any.

Ian

for chlorine to evaporate it takes about 3 days.
for it to cycle turn the filter on and wait 6 weeks.