Avoid Cycle With Large Addition of Fish At One Time

[swvahawker]

So I’ve had one of my tanks running for about 20 months now and I’m ready to give some bigger fish another try after getting ich about a year ago and going fishless for 100 days (I now quarantine appropriately). At this point I have 6 anthias and a scooter dragonet in a 125 gallon tank that is Apex monitored and dosed. I definitely am very well cycled and have many happy soft, lps, and sps corals.
So, I’ve been thinking a lot about when and how to add some tangs and have decided to try adding several tangs at once to spread out the aggression among several individuals and not allow one to establish territory and then add more later. I’ll be adding a medium-large purple tang, 3 small yellow tangs, a small powder brown, and a small hippo. I feel confident about the chosen fish and their habitat and am quite prepared to care for them properly. Having said that...
MY QUESTION is how should I go about managing the additional ammonia spike when all these fish hit the tank? The apex does auto water changes daily (1.5 gallon) to manage nitrate and I run a nyos skimmer and grow chaeto in a refugium. I’m just worried that my nitrifying bacteria aren’t as prolific as they need to be to handle the new fish load.
I’ve considered adding bacteria (microbacter, Dr. Tim’s, etc) to boost my population and I’ve also thought about dosing small amount of ammonia in the weeks leading up the addition to simulate fish waste. What do you think? Any other ideas?

 

[bluprntguy]

Dose microbacter or other bottled bacteria in the days leading up to and after introduction of the new fish. If you have a macro algae refugium, that should help with uptake too. I’d also have a hefty supply of zeolites on hand if they are needed.

Can’t you source juvenile fish and reduce the impact of the additions? I’ve seen some tiny tangs at the LFS pretty regularly.

 

[VegetaD]

Consider using a bright well brick in your current sump for at least a week with any live bacteria. That should help when you add the large fish

 

[taricha]

and I’ve also thought about dosing small amount of ammonia in the weeks leading up the addition to simulate fish waste.

Calculate carefully, but I lean toward this idea. You could also overfeed a flake food - it'll gradually release ammonia, but that would introduce a lot of other things too.

 

[Randy Holmes-Farley Verified Community Expert]

An alternative is to have something like Prime ready if ammonia rises, and take the plunge without making any preemptive changes..

 

[Lasse]

Once cycled - it is normally always cycled with some dormant bacteria if the load has diminish

It is not the fish themselves that will rise the NH3/NH4. It is the additional food that will do that. Just slowly raise your food regime to the fish you already have - during a week or two. Introduce your new fish - keep the same food regime and slowly rise it up to the amount there all are happy after a week or two. Rise slowly - during one or two weeks. There will be no spike - IMO - but in case - this is a good idea too

An alternative is to have something like Prime ready if ammonia rises, and take the plunge without making any preemptive changes..

Sincerely Lasse

 

[swvahawker]

Dose microbacter or other bottled bacteria in the days leading up to and after introduction of the new fish. If you have a macro algae refugium, that should help with uptake too. I’d also have a hefty supply of zeolites on hand if they are needed.

Can’t you source juvenile fish and reduce the impact of the additions? I’ve seen some tiny tangs at the LFS pretty regularly.

Yes, but as you may already know juvi tangs are fragile and hard to get eating. At lest in the experience of me and those I know. Thanks for the tips!

 

[swvahawker]

Consider using a bright well brick in your current sump for at least a week with any live bacteria. That should help when you add the large fish

I’ve definitely considered this and will likely do it. Thanks!

 

[Lasse]

Consider using a bright well brick in your current sump for at least a week with any live bacteria. That should help when you add the large fish

In which way will this help to get a higher nitrification rate before introducing the new fish?

Sincerely Lasse

 

[swvahawker]

In which way will this help to get a higher nitrification rate before introducing the new fish?

Sincerely Lasse

Yeah I suppose you’d need to overfeed or dose ammonium chloride as well.

 

[jccaclimber]

Yes, but as you may already know juvi tangs are fragile and hard to get eating. At lest in the experience of me and those I know. Thanks for the tips!

This is somewhat avoided by only buying fish you have seen eat, which is good practice anyways.
I second the advice that established tanks, especially those with some macro, are surprisingly good at not having ammonia spikes.
Feeding more in advance will help.
I feel like there is a risk of the purple beating on the yellows, but I might be overly nervous since nobody else has said anything about it.
Since your fish will presumably be nice and fast exiting quarantine you might also go light on feeding for a few days after introduction to the display.