Okay $2.79, way cheaper than I thought. You do have to buy the bacteria too ($22.46) for his method, but you're right, drop in the bucket in this hobby. And you can always get some live rock (not cheap, but you're buying regular rock anyways and how much of it has to be live? A couple good pounds of high surface area stuff at my LFS is about 7.99 per pound, and caribsea live sand costs about $40 for a 20lb bag, though you'd have to buy dead sand anyways or go bare bottom... it costs what it costs.
But you know what? OP wanted some hardy fish for a simple cycle, and I believe there are a lot of ways to practice this hobby.
So I'll choose to read friendly challenge, curiosity, and camaraderie in your post rather than arrogance and contempt. So with all due respect, sir, I believe I do know a thing or two about whether or not a fish based cycle is "cruel." Let's go to the peer reviewed literature...
After a brief review of the literature, the authors setup two Berlin style systems with deep sand beds and subjected them to various "perturbations," (adding rock, scraping glass, doing water changes, and a couple more minor things). They also included an established control tank (they state it has been up for years, but not how many) and natural seawater control (Bodega Bay, CA as their source water, which they also used for setup and water change). Their "live rock" was cured in a barrel for 2 months with periodic water changes. The authors sampled the bacteria (in triplicate) from the sand, walls, and mid-tank water (often times every day or twice daily) over a 90 day period and subjected samples to genomic identification. They tested a wide variety of water parameters daily during the initial setup and around "perturbations," and at minimum every 5 days otherwise. "Coral Pond 1" (CP-1 in figures) was setup 5 days prior to the second tank, "Coral Pond 2" (CP-2) but all "perturbations" were performed on the same day, thus CP-1 is given a slight head start. As an aside, aren't scientist great at naming things? Although the original paper does not include it, I have obtained this photograph of one of their tanks, below (Circa 2012, so some equipment is older than what we are used to, note the 14k metal halide fixture!?). All photo rights to the study authors. Other than their sumps being above their "displays" and not using traditional glass, please note, these are heavily stocked reef tanks very much in line with hobbyists. They put the corals in right away, not waiting for a completed cycle. The authors do not comment on specific stocking, I have reached out to them to clarify and have asked about any losses.
Their results indicate several points germane to our discussion.
Figure 1 indicates that in both tanks, the initial addition of 2 month cured live rock effectively and nearly immediately cycled the tank (Green doodle), despite the water starting with an ammonia concentration of 0.75 mg/L. In the author's words, "when the aquarium was seeded with live rocks... there was an immediate reduction in ammonia and nitrite levels." Addition of live rock (Sand disturbed?), water changes (presumably some ammonia in Bodega Bay?), and even scraping the aquarium glass produced some ammonia spikes (violet and red), which were promptly removed (my doodles and musings, not theirs).
There is a ton of other info on surprising microbial discoveries made by the authors. Pretty much every time they touched the tank the bacterial populations shifted in ways that were not detectable according to hobby kits, or as they put it, "No correlation between microbial shifts and water chemistry." The authors conclude that reef aquaria have multiple steady states at which they are stable and that microbial populations are highly redundant in terms of role. They also reported new taxa of microbes previously not known in aquaria, and demonstrated that the established microbial populations early in the cycle did not differ significantly from their years old established tank comparison, so a cycled tank is largely a cycled tank. Additionally, CP-1 with the head start on the cycle was not meaningfully different from CP-2.
The authors conclude that, "Our data set provides an overview of community changes over time, including the impacts of aquarium setup, conditioning, and routine tank maintenance such as wall cleaning and water changes. Notably, our results suggest that changes in microbial community composition do not always correlate with water chemistry measurements."
Hopefully what we have established is that 1) small ammonia spikes happen all the time in our tanks, 2) putting some cured live rock effectively cycles a tank in days, and 3) large shifts in aquarium bacterial composition happen beyond the hobbyists ability to detect both spontaneously and whenever we touch out tanks (the authors detected bacteria from the human GI tract in the tank, presumably from the scientists hands).
Let's talk about the ammonia spikes they noted. The authors report a maximum NH4 concentration of 1.0 mg/L, which accounting for pH, temperature, and salinity should get us to ~0.05 mg/L of NH3, the toxic part we care about for our fishies health. I used the "Free Ammonia Calculator" available courtesy of Hamza's Reef. This is right at the most conservative estimate (0.05-0.2 mg/L NH3) of what has been proposed as a "safe" range for "most" marine fishes. (Lemarie ́ G., Dosdat A., Cove `s D., Dutto G., Gasset E. and Person-Le Ruyet, J., Effect of chronic ammonia exposure on growth of European seabass (Dicentrarchus labrax) juveniles. Aquaculture, 229, (2004) 479-491)
There is great flux and shifts in understanding of the relationship between ammonia and marine fishes. I highly recommend the following review articles, which I found fascinating.
In short, we have made many incorrect assumptions about ammonia in marine fishies, most based off of our study of humans with liver failure. Some fishies, and particularly their larva, are very sensitive to even low concentrations of ammonia. Others seem to thrive in high concentrations. Indeed, analogs of proteins on our own red blood cell proteins (the Rh protein which gives our blood a + or - denotation) are theorized to help some fishes with their ammonia transport. Some fish adapt their gills quickly (usually < 3 hours in the species studied) to artificially high ammonia concentrations, while others exhibit gill changes which may not be adaptive. Other fish change their environment around them to make ammonia less toxic (the mudfish decreases seawater pH in its burrow all the way down to 7.0). The long held belief that hyperammonemia leads to fish respiratory distress has come under scrutiny of late, although fish do seem to have an area in their gills analogous to humans' means for responding to high CO2 levels which may affect their respiratory rate in response to ammonia.
Okay but clearly some fish die of ammonia poisoning... for the cruel people doing fish cycles, is one small fish possibly excreting enough ammonia to kill itself? I could only find numbers for the two-banded clownfish, but here goes... "Rates of ammonia excretion by the anemonefish Amphiprion bicinctus varied from a high of 1.84 μmole g−1 h−1 at 2 h after feeding, to a basal rate of 0.50 μmole g−1 h−1 at 24–36 h since the last meal." The authors state adult clownfish in typically weigh 11g and we feed these fish typically once per day, therefore we would expect ~300 micro mol/day of NH3, about 95% of which is converted to NH4 in seawater after leaving the fish, at pH 8.1, 25C, and 35 ppt salinity, so let's say 15 micro mol -> 0.26 mg per day (someone check my math, I assumed that over a 24 hour period there is a gradual decrease from 1.84 to 0.50). So this would depend on tank volume for concentration, and this is an adult clown so I'll go with live aquaria's recommendation for minimum tank size 30 gallons -> 113 liters (a big nano, but still), that gives you 0.26 mg / 113 L -> 0.002 mg/L ammonia per day that the tank has to process when cycling with an adult clownfish in a large nano tank.
(Roopin, Modi, Raymond P. Henry, and Nanette E. Chadwick. "Nutrient transfer in a marine mutualism: patterns of ammonia excretion by anemonefish and uptake by giant sea anemones."
Marine Biology 154.3 (2008): 547-556.)
Anyways, I had fun reading and studying this. Learned a ton. And it's entirely possible my math is wrong or I've read the lit wrong, missed something etc. Feel free to correct me.
But bottom line from my review,
@mfrumkin can go get whatever dang little fishy he wants and cycle his tank any number of ways. And he'll probably take care of his fish best when he's not branded as *cruel* two weeks after he's joined our community.
Cheers
