How many fish should you add at once to a freshly cycled 125G tank?

[ReefWithCare]

Hi All,

I'm in the process of cycling a 125G + 55G sump aquarium. I'm using bacteria and ammonium Chorline to cycle until I go from 2PPM to 0PPM ammonia in a 24 hour period. Once that happens, how many fish should I add at once?

 

[mcarroll]

Any live rock? Plans for coral?

I wouldn't add more that 1-2 at a time. And not until there's been a few other more minor critters in there for a while first...a few CUC, for example.

Build slowly and in small steps.

The answers to the questions at the top will define how you're proceed from the start above.

 

[Flippers4pups]

Hi All,

I'm in the process of cycling a 125G + 55G sump aquarium. I'm using bacteria and ammonium Chorline to cycle until I go from 2PPM to 0PPM ammonia in a 24 hour period. Once that happens, how many fish should I add at once?

Cycling may and most likely will take much longer than 24hrs to complete. Go slow and wait till you see nitrate climb, nitrite and ammonia hit zero and stay there. Can take weeks for that to fully happen.

 

[ReefWithCare]

Cycling may and most likely will take much longer than 24hrs to complete. Go slow and wait till you see nitrate climb, nitrite and ammonia hit zero and stay there. Can take weeks for that to fully happen.

Sorry I need to clarify. So dr. Tim’s instructions calls for a full dose of ammonium chlorine after I hit 0 ammonia and 0 nitrites. Then that ammonia should get processed out within 24 hrs and if that happens it says you can add fish now - but it didn’t say how many you can add.

If the answer is 1 or 2 fish, I’m kinding feeling the second dose of ammonia is unnecessary and would just add more nitrates to the system

I think the shrimp method is drop he shrimp until you hit 1 PPm Ammonia then cycle the tank until you hit 0 ammonia and nitrites.

 

[lapin]

Hi All,
I'm in the process of cycling a 125G aquarium + 55G sump . I'm using bacteria and ammonium chloride to cycle until I go from 2PPM to 0PPM ammonia in a 24 hour period. Once that happens, how many fish should I add at once?

3 small ones or 2 med size. Try not to overfeed. Test for ammonia every few days to gauge how your tank is reacting to the added bio load

 

[Flippers4pups]

The idea in cycling is establish enough of the nitrifying bacteria colonies to break down decaying matter, to sustain the bio load placed on them.

In cycling, a progressive order must be established of nitrifying bacteria. Ammonia is the fuel, from wastes of decaying matter, fish poop and pee, corals and foods fed. From the break down of these by specialized bacteria produces nitrite, then different bacteria break nitrite down to nitrate.

The establishment of each of these colonies takes time to sustain. If not enough of any of these to sustain, a collapse in the cycle will happen and the cycle must start again. In most cases it takes a month to establish enough of these colonies to be self sustaining, let alone take on a bio load.

To answer your question, I wouldn't rush this process and be patient to allow these colonies to become established completely before adding fish, inverts and coral.

Once the tank is fully cycled, then a couple of fish is we're you start. If the tank isn't fully cycled and you add fish too soon, the nitrifying bacteria can't keep up and ammonia will rise. Ammonia, even the smallest amounts is extremely harmful to fish and can burn their gill plates or even kill them.

Take it slow and do it right.