Best Fish to Cycle With

[Coralreefer1]

Something I have learned is you have to do things slow and not cut corners. Having said this however, I have a story to tell.
In the past, I have always cycled my tanks the so called old fashioned way. Either using a Damsel fish which way back when was what my local pet shop employee told me to do. Then I switched to using frozen shrimp or uncured live rock.
Recently, in my 4 and 10 gallon cube tanks, all I did was take some rock from my established 14 gallon tank with sand and some water also from that same tank.
I never had any cycle, atleast that was detectable as I never lost any coral, fish or invertebrates. My assumption is that I had enough bacteria, both aerobic and anaerobic to support the light bioload in my newer tanks.
These tanks have now been up and running for 6 months or more.

 

[Smarkow]

The OP didn’t indicate that he knows or used this method. His one line question indicates he’s looking for other fish to cycle the tank. Using already cured live rock to avoid the initial cycle or lessen the initial cycle is certainly possible, but there’s absolutely nothing in his post indicating that is what he’s doing. How do you know he didn’t just set up a tank with dry rock and sand?

Yeah good call, probably not a great assumption on my part.

Again, this assumes that one is starting with already cycled, live rock to help process ammonia. Dead dry rock without bacteria is not going to process ammonia and it will build up. Most people don’t call this “cycling” a tank. It’s using already established, cycled live rock in a new tank to avoid or lessen the initial cycle. Also, you included only fish in your calculation. You didn’t include excess food that inevitably finds its way into the aquarium, which will increase ammonia significantly more than fish. How much will it increase ammonia? I don’t know. It’s your argument and it’s missed a critical issue.

So this is actually the part that has really occupied my thoughts this morning, and it is a critical issue. This is the mechanism I think accounts for how a single fish introduced into an otherwise "sterile" closed marine environment will start the nitrogen cycle. Ingredients on fish food in terms of protein by weight are really all that is needed to make a decent approximation of the overall nitrogen balance. To some extent, as long as the fish is getting adequate nutrition to grow and thrive, whether the fish eats the food or whether it decomposes is actually irrelevant to the overall nitrogen balance of the system.

So bacteria does not come from thin air (Thank you again Louis Pasteur). But the surfaces of humans and fish, the GI tract, and pretty much every surface is covered with bacterial hosts. Quite frankly, short of hermetically sealing our boxes of water and rock... we cannot stop but have a cycle. But lots of companies are perfectly willing to make that cycle easier and more predictable for the hobbyist for what is (by reefing standards) not an unreasonable charge for production, packaging, shipping, retail salaries, reliability, and quality guarantees. Which is correctly noted by @bluprntguy among others here. What follows is not an argument for what constitutes "Best Practice" or path with most guaranteed success. However it is a scientifically validated, evidence based pathway which is OBJECTIVELY NOT CRUEL or inhumane.

Here goes, citations and graphics below, as this is much more general information. The classes of gamma and beta proteobacteria are gram negative, ubiquitous, and diverse yet also share common metabolic pathways around the fixation of nitrogen. Many dozen genera within these two related classes have major effects on human and nonhuman animal health, digestion, wellness, the environment, and geochemistry. Members of these classes process our sewage and are directly responsible for filtering water for almost half of all fish farmed for consumption by humans. Members of the Beta proteobacteria class are found in both terrestrial and marine environments, including Nitrosomonas species which are obligate oxidizers of ammonia to nitrite for their energy. Another member of the Beta proteobacteria is Nitrosospira sp, every member of this genus is known to oxidize nitrite to nitrate, and some species were the first bacteria found to completely convert ammonia all the way to nitrate. Gamma proteobacteria are the most common class of microbe found on the skin of coral reef fishes. Gamma proteobacteria, including nitrosococcus sp., are also ubiquitous in marine environments and all convert nitrite to nitrate. You may later note these species are the ingredients listed in biospira (screenshot below) while Dr. Tim and Brightwell do not disclose their bacterial ingredients, which is sort of funny in the age of google, as these are not really trade secrets :)

Additionally, many species of marine, and specifically coral reef fishes, are present in large numbers in the fish GI tracts. Fish GI tracts are short and often highly inefficient, and indeed coprophagia (the eating of feces) is widely practiced and found to be natural and nutritious for most marine species. The short and inefficient GI tracts of fish mean that lots of bacteria and partially digested food is released into the water. Nature abhors waste, and this partially digested food can be reinvested by other fishes. Typically piscivore and zooplanktivore feces are eaten by herbivorous fish species preying on predominantly red algae, whose feces are eaten predominantly by detritivores, consumers of benthic inverts, and and lower herbivorous fish (brown algae grazers). In this way, bacteria species and critical micronutrients remain in circulation among reef creatures with otherwise poor digestive tracts before ultimately settling out as food for coral and benthic inverts. This is one of the critical nutrient recycling systems that enables isolated coral reefs to maintain biomass in otherwise nutrient poor, isolated waters. During this process, bacteria have abundant access to nutrients and may replicated in the water column, pass from fish to fish, or settle out into the substrate, where they may be reingested by parrotfish and coralivores and reenter the water column and GI tracts of free swimming fishies.

Many species are present in the GI tracts of a coral reef fishes, just like the human body. Indeed there is great crossover amongst the human GI tract microbiome and marine fish microbiome, with species such as pseudomonas (infamous for biofilms), vibrio, aeromonas, moraxella, and campylobacter being examples. Indeed many genes and immune system components are shared between human and marine fish intestinal tracts, including the GI lymph tissue system and signaling components, chemokines, and receptors (although the human GI tract is significantly more anatomically complex and highly efficient vs a marine fishes). However, symbiotic and commensal bacteria in fish are known to cause many human diseases and vice-versa. Many of these bacteria share a common ability to take part in various components of nitrification and denitrification, maintaining N balances in our tanks, on coral reefs, and in human and fish GI tracts.

So the fish we put into our reef tanks are fully capable of introducing a wide variety of nitrifying bacteria to our previously "sterile" tanks via their skin/epidermis/mucus and their feces. Our hands also transfer terrestrial nitrogen fixing species from the soil to the marine environment. Introducing these bacteria to a previously uncolonized rock/sediment/surface/water column in the setting of nutrients (fish poop from food, ammonia from GI tract and gills) sets off a land race among the competing bacteria which is capable of achieving many different steady states. The question for the health of our tanks and inhabitants are whether or not the bacteria will divide in time to create an environment capable of processing the ammonia. If there is a small fish with low net ammonia production in a comparatively high water volume then the tank will almost certainly find a steady state cycle with no stress caused to the fish. Knowing the fishes' weight and the tank's overall nitrogen balance (which will account for inevitable uneaten food) plus the rate of division for relevant bacterial strains plus the tank's water volume should enable a rough napkin sketch estimate of whether the practice of fish only cycling is likely to cause any appreciable stress to our pet.

Of course, you can always buy some bacteria in a bottle which will likely increase the odds of success. Brightwell's Microbacter and Dr. Tim's do not disclose their ingredients, though a cursory search of the literature indicates they are likely the same species. Kudos to instant ocean bio-spira which at least acknowledges the use these bacterial strains on their bottle. If these bacteria make it from the water column to the rock and sediment surface (skimmers off!) and are viable with adequate ammonia, then they are likely to produce a faster cycle. Of course you could just put cured live rock in as well.



Below is a breakdown of some recent lit:

Above, abundance of bacterial species on the skin of 45 common reef fish. Gammaproteobacteria (the most predominant) are often composed of obligate ammonia oxidizers. Some other nitrogen fixers are present in other families. (Chiarello, M., Auguet, J. C., Bettarel, Y., Bouvier, C., Claverie, T., Graham, N. A., ... & Villéger, S. (2018). Skin microbiome of coral reef fish is highly variable and driven by host phylogeny and diet. Microbiome, 6(1), 147.)

Below, bacteria involved in marine nitrogen fixation (Schreier, H. J., Mirzoyan, N., & Saito, K. (2010). Microbial diversity of biological filters in recirculating aquaculture systems. Current opinion in biotechnology, 21(3), 318-325.)


And lastly common fish GI bacteria, below (Pérez, T., Balcázar, J. L., Ruiz-Zarzuela, I., Halaihel, N., Vendrell, D., De Blas, I., & Múzquiz, J. L. (2010). Host–microbiota interactions within the fish intestinal ecosystem. Mucosal immunology, 3(4), 355.)

 

[MnFish1]

@MnFish1 - I see you referenced an older thread. Perhaps you can send the link? I’m interested to see.

no problem. - realize that you will have to read a ton to get to the results - it was kind of carefully designed. I'll try to find the results post - it might take a bit. there is a summary here I think if its correct: https://www.reef2reef.com/threads/bacteria-in-a-bottle-myth-or-fact.403226/

 

[Dr. Reef]

Results are on page 1 post #3

 

[vic5hands]

Gobies

 

[vetteguy53081]

Damsels are and can be tank nightmares. Honestly, Black mollies are great algae eaters, cheap and thrive well in saltwater. Also brackish fish such as Mono sebae or scats. These are inexpensive, disease resistant and will help seed your tank

 

[FrancineJ]

In this day and age there is NO reason to use fish at all under any circumstance as far as I can see....

Scenario 1- all dry rock- I have personally cycled tanks of all dry rock (Caribsea LifeRock) with just Dr Tim’s bottled ammonia (for convenience sake but you could use any unscented ammonia) and Biospira- had tank cycled in under a week.... no fish involved

Scenario 2- Live Rock... when it curing throw in some Biospira and again it will be cycled in under a week....

I have helped people start many different kinds of tanks all with Biospira and I’ve never had to use any fish....

 

[ScottR]

no problem. - realize that you will have to read a ton to get to the results - it was kind of carefully designed. I'll try to find the results post - it might take a bit. there is a summary here I think if its correct: https://www.reef2reef.com/threads/bacteria-in-a-bottle-myth-or-fact.403226/

I read through the study but it was done with ammonia and not a fish. But nevertheless, seems more than plausible. Also I can say I’ve used some of the products mentioned and never had trouble cycling a tank. Perhaps we worry too much when cycling a tank and it’s not as big of an ordeal as it seems.

 

[Paul Sands]

Pic from round one of the “study” seems to indicate that three out of four bottles of bacteria failed to even make a dent in the ammonia levels. I haven’t re-read the thread, but didn’t it take the “advanced” aquarist doing the study multiple rounds to figure out what went wrong?

Why potentially subject a fish to this process when there are effective ways to insure a tank is processing ammonia adequately before you even introduce the fish?

 

[DSC reef]

Pic from round one of the “study” seems to indicate that three out of four bottles of bacteria failed to even make a dent in the ammonia levels. I haven’t re-read the thread, but didn’t it take the “advanced” aquarist doing the study multiple rounds to figure out what went wrong?

Why potentially subject a fish to this process when there are effective ways to insure a tank is processing ammonia adequately before you even introduce the fish?

I'd suggest reading the entire thread, you might learn something... Alot of great info and time dedicated by members who love to help others out here on R2R

 

[Paul Sands]

I'd suggest reading the entire thread, you might learn something... Alot of great info and time dedicated by members who love to help others out here on R2R

I did. And I agree. A lot of time was spent doing this.

 

[Dr. Reef]

Short answer to Paul
Some products did and will fail in sterile tanks but as soon as carbon source is introduced they work just as well as the best in sterile tank. Difference is Heterotrophic bacteria vs true nitrifier bacteria.
I realized that much later in study and by talking back and forth with manufacturers that conducted their own studies due to this thread/study.
One thing I can say without a doubt is ALL products I tested will cycle a tank with carbon source either in form of fish or food etc but only few will work in sterile tank. Most all of them reduced ammonia to safe levels within 24 hrs, starting at 2ppm.
Like I said before 0.69ppm is required for a hardy fish like clownfish or damsel to start hurting due to ammonia. Under that amount is irritating but not harmful.
In a new setup with fish and bacteria added together, ammonia will probably never reach dangerous levels thus keeping fish alive and bio filter developing.

 

[ScottR]

Lots of info for the OP and also noobs to sift through. @Dr. Reef - could you explain in a nutshell the best practice? And hopefully we can just leave it at this. This thread could go on forever. :p

 

[Dr. Reef]

@ScottR
My personal preference is with fishless cycle.
But with the new technology and development of these bacteria in bottle, one can safely cycle a tank with fish in tank.
Caution: bottle bacteria can only do so much so one cannot fill a tank full of fish and pour a small bottle bacteria and expect to make it.
If someone wants to go this route they should setup a tank and introduce small one or two fish with bacteria and let it develop a Bio filter before adding more fish.
If I was to cycle this way I would choose tank raised clownfish. (2 at most in a new tank)

 

[Coastie Reefer]

But it takes 3-6 weeks or wasted time.... IMHO

A 3-6 week exercise in patience is not wasted time in my opinion

 

[T Carey]

Given that the OP has other tanks it seems to me the easiest solution would be to take a cup full of sand from an existing tank and spread it around in the the new tank. I like yellow tailed blue damsels because I have found them to not be aggressive like most other damsels. So for me they make good community fish. Another option that has not been mentioned is to set up a foam filter in one of the existing tanks for a week then move that into the new tank. The foam could be placed in the filtration area so it could be out of sight.
In all of the above scenarios some sort of living ammonia source would be needed to keep the bacteria growing.

 

[Lasse]

The key to these experiments was that they started with high levels of ammonia - and waited for them to fall. If you start at 0 ammonia - and bacteria - the ammonia level should never increase to the point where its a problem (which is the goal). No one wants to be cruel to a fish.

@ScottR
My personal preference is with fishless cycle.
But with the new technology and development of these bacteria in bottle, one can safely cycle a tank with fish in tank.
Caution: bottle bacteria can only do so much so one cannot fill a tank full of fish and pour a small bottle bacteria and expect to make it.
If someone wants to go this route they should setup a tank and introduce small one or two fish with bacteria and let it develop a Bio filter before adding more fish.
If I was to cycle this way I would choose tank raised clownfish. (2 at most in a new tank)

These two quotes are a good summary and thank you for the in deep explanations @Smarkow. But back to the OP question. You can use the fish of your choice as long as it is well feed, healthy and not shy. In your case with access to both rocks and sand from existing aquariums – it is easy to make your own “bacteria in the bottle”. The NH3/NH4 input is done with your feeding regime, very small in the beginning and raised during time. I think this was the conclusion already from post #9 and #13 :)

Sincerely Lasse

 

[Paul Sands]

Short answer to Paul
Some products did and will fail in sterile tanks but as soon as carbon source is introduced they work just as well as the best in sterile tank. Difference is Heterotrophic bacteria vs true nitrifier bacteria.
I realized that much later in study and by talking back and forth with manufacturers that conducted their own studies due to this thread/study.
One thing I can say without a doubt is ALL products I tested will cycle a tank with carbon source either in form of fish or food etc but only few will work in sterile tank. Most all of them reduced ammonia to safe levels within 24 hrs, starting at 2ppm.
Like I said before 0.69ppm is required for a hardy fish like clownfish or damsel to start hurting due to ammonia. Under that amount is irritating but not harmful.
In a new setup with fish and bacteria added together, ammonia will probably never reach dangerous levels thus keeping fish alive and bio filter developing.

You’ve never had a bottle of bacteria that was completely dead because it was likely stored incorrectly at the store or somewhere along shipping? I have. On numerous occasions.

The big issue is the “probably” portion of your response. Is that enough to put a fish in a new tank, dump in some bacteria, and then leave for a week or not test ammonia for the same time? I certainly wouldn’t. Is it OK to “irritate” an animal in an uncycled tank with a “bit” of ammonia because we wanted to save a week off our new tank set up? I think not.

Can you cycle a tank with a fish without killing it? Yes. That’s a different question than “should you”

There are better ways. I’m glad you at least agree that fishless cycling is at least preferable.

 

[Smarkow]

Results are on page 1 post #3

Really cool thread, thanks :)
Seems like I’m about to have a really *unproductive* afternoon of reading

 

[reacclimating 2 the hobby]

+1 for fishless cycle