A few notes on fish-in cycling and tank tricks.

[Maff]

My recent return to aquariums and the time you need to dedicate to your fish has brought back a lot of memory. Most of my experience was with marine tanks in the past but I have had a quite a lot of experience with freshwater.
Lots of things have changed since I had my last tank, I had two power heads running and an under gravel tray which has now been surpassed with more efficient canister designs. The amount of available species has doubled compared to what I stocked, I had guppies, platties, red tailed sharks, neon and cardinal tetras, swordtales and plecs. The amount of cat fish available these days is incredible. I never had access to Corydoras back then or many of the other species available now.
Another thing that has changed is fishless cycles, we never did it back then, it was always fish-in cycles and in fact it wasn't called fish-in back then, it was just called tank cycle because fishless was literally unheard of.
My experience with fish-in cycles is what I want to talk about today. If you are at work a lot and don't have a lot of time around the tank I used to tell people not to bother with tropical fish - period. Because of fishless cycles that can be worked around if you're at work a lot, you can make it work for you I suppose.
If you do a fish-in cycle then you need a lot of time around your tank, you can't really nip off to work for 12 hours during the early stages for example. Why? The first 12 hours of a fish-in cycle are often critical, sometimes its between 12 and 24 hours that are critical, sometimes its after 24 hours it becomes critical to be there - all the time.
I've known people go to work during the early stages and hit above 1ppm ammonia when they come back from work. If you really care about your fish, by this time it's too late and the damage is done. Those fish sat in 1ppm or even less of 0.5ppm for 12 hours are more than likely going to die or have permanent damage which leads to a shorter life.
What do I do? I do have a job but I take time off work to care for my fish during cycles. I know that fish-in cycles can be hard on fish and if you are not there then their suffering increases drastically.
Not everyone has the freedom to do this and I understand that but like I said - if you don't have the freedom do a fishless.
Some could argue that I should do a fishless cycle myself and cut out the risk but having read about it, you can end up with stalling or even ammonia spikes after a fishless cycle completes. I have no experience of it and don't know what I'm getting myself into which raises uncertainty in my mind.
I decided to do fish-in for the simple reason I've never had fish die on me in either marine or freshwater but that meant getting up at 3am and doing tests then PWC's especially with marine, you only ever get out what you put in - in terms of hours spent and hours enjoying your fish.
So a few tips that I can remember from my past in terms of tank tricks.
Get the biggest tank you can afford, don't think smaller is better in aquariums. Bigger is better especially with cycling because toxins are less concentrated. Seed your filter with established media and bacteria supplements.
Regarding stock, unless you are dealing with marine don't get one fish at a time. It would take you years to do a step by step bacteria increase fish by fish. Get 4 to 5 juvenile hardy fish in your large tank. We do not want ammonia to get anywhere near 0.5ppm
never mind 1ppm. This is when you need to be around the tank 24/7. In the old days we never let it get above 0.25ppm because we didn't have things like prime. Because of things like prime you have a little more freedom but still it is important to keep below 0.25 especially if your PH is high. Do not feed for 48 hours after fish are in the new tank.
Feeding. Only feed every two days and if the ammonia spikes very early then stop feeding altogether. Monitor for ammonia no less than 6 hours after you feed every time you feed.
Testing. I see a lot of people telling others to test every 24 hours or every 12 hours during cycle. If you really care about your fish during cycle you need to test way more than that. I know kits are expensive but so are fish and no one wants to see fish suffer so it goes back to the 24/7 thing again. Test 6 hours after they've been in the tank, test 6 hours after they've been fed and sometimes it means getting up at 6am to do it. Once you miss a 0.5ppm ammonia peak when it first arises then you've missed the boat and damage is done but again prime can let you off the hook with that. If its bedtime and you see a spike of 0.2ppm ammonia don't wait till the morning to put prime in, do it then. Chances are it will be double that reading by 6am the next morning. Water change in the morning.
Same with nitrite spikes, test 4 times a day around the clock, nitrite is lethal in small doses and once your fish have been sat in it for a number of hours you can forget it. Again prime is a savior and gives you 48 hours time to change water. Sometimes with nitrite you might need to do a 3/4 water change every day depending on spike levels. 24/7 monitoring comes into play again, you can't afford to be at work when you hit a nitrite spike, you'll pay for that.
Tank tricks and adding more fish. If you get a stable tank for a week don't add more fish just yet. Increase your feeding patterns to once a day, twice a day and three times a day. Yes you read that right - three times a day. Why? Each time your feeding patterns go up then the more ammonia is in the tank and the bigger your bacteria colony will get. You will spike your ammonia for sure and you have to deal with it like stated above testing every 6 hours and acting accordingly. Each food increase replicates adding one more fish to the tank and the colony will build accordingly.
Once you have got your ammonia levels and nitrite 0 and 0 respectively do a 3/4 PWC and stop feeding the night before you get more fish. Add the fish (same rules apply as adding your first fish), do not feed for 48 hours. Check your levels every 6 hours as before. The ammonia spike will be less than normally adding fish. The increase in feeding has now been replaced by fish stock and the bacteria levels are more suitable. You can add supplementary bacteria at the same time as your new fish go in to lighten the load. Follow the procedures as you did for your first fish and do the same every time you put more fish in especially increased feeding to build bacteria. Always check your filter pads for blocking.
If you don't have time to do any of the above with fish-in cycling then it is best not to bother with it at all.

 

[mcordelia]

These are great points! The only thing I would disagree with is the number of fish. Bacteria grow at an exponential instead of a linear rate, so going from the bioload / bacterial population to support 1 fish to 2 fish takes the longest, and going from 3 fish to 10 fish takes a logarithmically shorter time.

In other words, if you first cycle with 2 fish, and then you add two more fish, your bacterial doubling time / stabilization time may be 1-2 weeks. But then, going from 4 fish to 6 fish may only take 1-2 days, since you a) have a larger established population, so you have more bacteria replicating and b) you won't necessarily have to double your bacterial volume to support the new ammonia produced.

An example schedule could be (this is just an EXAMPLE, whether this is appropriate for you depends on whether you have fast-growing plants, how big your tank is, how sensitive your fish are to parameter shifts, etc):
day 1: add 2 hardy fish, use prime and frequent water changes, and keep the ammonia below 0.5 (because too much prime ultimately isn't good either!)
day 40: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 2 more fish.
day 54: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 2 more fish.
day 62: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 6 more fish.
day 69: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 10 more fish.
and so on and so forth.

This all being said, there is more than one way to skin a cat! example is my total fail of recently starting up my 20g tank (I think the leading cause was impatience, but all's well that ends well, right?) I think someone's choice in cycling ultimately comes down to their personality, and how much time/money/stress they want to expend on their tank to get it established. Fishless is definitely the cheapest, least stressful, and longest, with planted/silent probably falling in between, and fish-in (especially with no plants) is often described by people online as being wicked stressful, but sometimes people find themselves in a situation where fish-in is the only way to go, and I think it's important to provide information for how to make it work when that is the case

Thanks for your input and tips!!

 

[Maff]

These are great points! The only thing I would disagree with is the number of fish. Bacteria grow at an exponential instead of a linear rate, so going from the bioload / bacterial population to support 1 fish to 2 fish takes the longest, and going from 3 fish to 10 fish takes a logarithmically shorter time.

In other words, if you first cycle with 2 fish, and then you add two more fish, your bacterial doubling time / stabilization time may be 1-2 weeks. But then, going from 4 fish to 6 fish may only take 1-2 days, since you a) have a larger established population, so you have more bacteria replicating and b) you won't necessarily have to double your bacterial volume to support the new ammonia produced.

An example schedule could be (this is just an EXAMPLE, whether this is appropriate for you depends on whether you have fast-growing plants, how big your tank is, how sensitive your fish are to parameter shifts, etc):
day 1: add 2 hardy fish, use prime and frequent water changes, and keep the ammonia below 0.5 (because too much prime ultimately isn't good either!)
day 40: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 2 more fish.
day 54: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 2 more fish.
day 62: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 6 more fish.
day 69: if cycle is complete and tank supports the existing bioload with normal feeding patterns and water changes, add 10 more fish.
and so on and so forth.

This all being said, there is more than one way to skin a cat! example is my total fail of recently starting up my 20g tank (I think the leading cause was impatience, but all's well that ends well, right?) I think someone's choice in cycling ultimately comes down to their personality, and how much time/money/stress they want to expend on their tank to get it established. Fishless is definitely the cheapest, least stressful, and longest, with planted/silent probably falling in between, and fish-in (especially with no plants) is often described by people online as being wicked stressful, but sometimes people find themselves in a situation where fish-in is the only way to go, and I think it's important to provide information for how to make it work when that is the case

Thanks for your input and tips!!

Some people might think fish are expendable during a fish-in cycle and spend far less time caring for them as they should. Anyone who thinks like that shouldn't have fish in the first place IMO.
No fish are expendable no matter how cheap they are and when I hear of people doing this I get angry. If you do a fish-in cycle you must be prepared for a lot of hours and effort not to stress the fish.
Maybe fishless cycles were invented for people who can't be bothered or don't have the time to do fish-in or maybe they are a safer option in the long run but one thing is for sure which ever path you choose you will eventually be doing a fish-in because I doubt very much you could fully stock a tank after a fishless cycle. After a fishless cycle you might end up with enough capacity for half your stock or less and that means the rest of your stock becomes fish-in anyway. With this in mind you might as well have done fish-in from the beginning and got use to the pro's and cons.
This is where my main points become important. If you work a lot and do a fishless cycle, spending large amounts of time away from the tank just checking levels every 24 or 12 hours then you stock it with 50% of it's capacity, where are you going to find the time to monitor the tank when you start adding the rest of your stock?
Your levels need monitoring the exact same as an initial fish-in because not only are you risking the new fish, you are risking the established fish - it becomes an even greater risk.

 

[mcordelia]

I agree with your points, but I also think that there is a bit more variability both within personalities and within the hobby / goals of people to suggest that fish-in should be the way to go.

For example, for my 125 gallon, I absolutely plan to understock it because I know that with my lifestyle and what next year entails for me there will be no way that weekly water changes are a reality. In this regard, your point about "having to reach stock" would be moot.

Another thing I want to circle back to is the exponential growth of bacteria. This is not a linear phenomenon. Growing enough bacteria to support 2 fish takes 6 weeks, but growing more bacteria (to support 12 fish for example) is only an extra 2 weeks for example (the specific times depend on the fish, your tank, and other variables). Thus, while yes, an established aquarium is ultimately continuously going through a fish-in cycle (the bacteria age and die off, and new ones take their place, and small changes like fish growing and fish dying, as well as aquascape changes etc. make it a dynamic and ever-changing system), I think the question herein lies in what is an individual's choice for reaching the "tipping point". Once a population of bacteria is established, it can easily grow in a day or two to quickly accommodate changes in ammonia. But getting to that "established" or "tipping point" phase is what creates the difficulty, and I can see the argument why a lot of people would prefer a more "set it and forget it" approach.

I think the third important point to consider is cycling a tank for fish such as discus, puffers, or other more challenging/expensive fish. I think it would be unethical to purchase fish to cycle the tank with, only to then either return or cull said fish after they have "served their purpose", so that fish which are more sensitive to parameter changes can be introduced. I think fishless cycling is an excellent approach when the goal is to introduce sensitive or demanding fish species.

Ultimately, I think it's wonderful that in today's day and age we have more than one option available to us for cycling a tank! Though I personally prefer fishless cycling, if you check out my 20gal journal I literally just went through a silent cycle that I then converted into a fish-in cycle mostly out of impatience. It's common for people to think that their approach is the "best" approach, but more useful to the community in my opinion is a general stance of what works best for someone may not work best for someone else, and being able to support whatever approach is the best fit for someone's lifestyle or hobby goals should be the aim

 

[Maff]

That's a fair point. Every tank and every individual is different with different sets of circumstances. There is no golden rule which works for one person which will automatically work for the rest. Trial and error is not a option we can take when animals lives are at stake here.
My point being if you do a community tank like my friend did, ran a fishless cycle successfully then added 5 small fish then came home to an ammonia spike 1ppm that they'd been swimming around in all day, that's the kind of uncertainty I don't like and what I've been reading about. No one can afford to do that to fish least of all beginners. In contrast my fish-in cycle had no such problems because I work to simple principles. One being I'm not swanning off to work at critical times when those fish need my attention, two being I monitor the conditions more often than most and never allow myself to get into that situation in the first place. Its no good having general principles in the hobby that state its OK to measure conditions every 12 hours, that simply isn't the case. You measure when you feel things are at a critical point and you measure more and more depending how critical it gets in there. You can kill a tank full of fish in 6 hours and not even know until 3 days later just by not realizing you hit a massive nitrite spike, I've seen it happen in my father-in-laws tank more than once.

 

[Maff]

Here is where the uncertainty lies with me and others too from what I've been reading concerning fishless. If you do a fish-in using a large tank, I take my first reading 6 hours after the fish are in. I can roughly see the rate at which ammonia builds and I can act. I take another at 12 hours and see if the build up of ammonia is the same or increasing and again I can act accordingly.
With the fishless cycle there seems to be some confusion as to how many fish you can actually put in after the cycle completes and there seems to be a lot of advice out there concerning measuring toxins and when you should do it i.e 12 or 24 hours after you put them in. If it was me it would be 6, 12, 18 and 24 hour measurements because I would not be able to live with myself not knowing what my tank is doing to my fish.
It's a funny carry on if you ask me but that's just my opinion.