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Newly Cycled Tank

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Dec 26, 2019
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Hi all, been cycling a 230l tank over the last 5 weeks. I have been dosing ammonia to 4ppm. The nitrite and ammonia are now dropping to 0 in a few hours. My question is when I stock fish I will obviously do it gradually however will the bacteria start dying off as the fish load I put in wont be dosing to 4ppm anymore. I was going to start by adding around 10 of my Cory's into the tank wait a week or two then add bosmani rainbows over. Should I add a bigger biomass at first or do it gradual like I'm planning? Sorry for the noob question it's been about 6 years since I cycled my last tank.
Welcome to TFF. Someone should respond sometime today.

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Since your tank is cycled you can do a large water change (to get rid of the nitrates) and add both species at once.

To answer your question the bacteria go dormant if there is not enough food. As long as you have some fish in the tank they won't die off completely but their numbers will reduce. They do multiply quickly once more food is available. So it really is your choice if you want to add them all now or do it gradually.
The idea behind fishless cycling with ammonia is that the tank will grow more bacteria than required by a sensibly stocked tank. (It won't have enough bacteria for a grossly overstocked tank :) ) All the proposed stock can be added at the same, though there are some species that will fare better in a tank that has been running for a few months.
It is also sensible not to fully stock as you'll only see a must-have fish once the tank is completely full :D

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