Fish In Cycle ?

[jackson 10]

just read a post on another website and a guy was talking about he had around 9 fish in a unclycled tank and rekons it speeded up the proces of cycling rather than a fishless cycle no fish was lost he rekons and now 2 weeks later his tank is fully cycled

could this be true?

 

[waterdrop]

In one sense there is no such thing as "speeding up" or "slowing down" a cycle, since the rate at which each species divides is a fairly fixed number. But in another sense, that of the overall process, then the process can be speeded up by a larger number of cells at the start or a better growing medium during the process, which encourages more successful cell division in all cases.

Fish-In cycling has been practiced since the very beginning of the hobby. In the earliest years, it was done out of ignorance of the process that was going on. Subsequently, prior to the 1980's, no practical alternative had been worked out and so many hobbyists learned it as the "correct" way of cycling. Fish-In cycling subjects the fish to greater amounts of permanent gill and nerve damage than would otherwise happen, either in the wild or in a fishless cycled tank. While damage from nitrite poisoning is pretty universal I believe, the gill damage from ammonia poisoning varies greatly by species, with some being much more sensitive than others. In either case however, Fish-In cycling often results in fish deaths.

~~waterdrop~~

 

[OldMan47]

The cycle time actually cannot go slower without fish in because you can only grow the needed bacteria so fast. If the ammonia processing bacteria have an excess of ammonia, they will expand at about two fold every 24 hours. That is based on the ammonia present, not on the source of that ammonia. The same principle applies to the nitrite processing bacteria. The instant gratification is present when you start with fish if that is your main interest. The other thing that comes up in cycling tanks is stocking rates. At 5 ppm ammonia for a fishless cycle, you could theoretically stock your tank fully when the cycle is complete. At water changes daily to control ammonia and nitrites for the fish's health, when you get stable and stop having poisons and stop losing fish, you are only cycled to the level of the tank's population. The next thing you do after that on a fish-in cycle is to very gradually, over months, increase the population and go through multiple mini-cycles that need your attention because you never got a really large bacterial population.
Either method takes the same time to reach the first cycle stability point but the work involved and subsequent stock limitations make me favor fishless.

 

[Schmill]

For the fish obviously the best method is fishless cycling as it carrys no risk of damage to the fish.

As for speed, as said above the actual 'cycle' / growth of the bacteria will not be accelerated or slowed by having fish or not having fish in the tank.
What can make it seem quicker is for when you reach 'stable water' conditions, that of having no ammonia and no nitrIte.

Lets say you want to stock your tank to 100% of it's stocking capacity.
For arguments sake lets say a 100% stock will produce 5ppm of ammonia every 24hrs (can you see where I am going?)

So to cycle, you could add 5ppm of ammonia, only increasing it when it drops to zero, until you get perfect water.
or
You could stock with all your fish, and do many massive water changes, replace the fish as each one dies, (to keep the levels the same), and then eventually get perfect water. (Although I think this would take longer due to the frequent 'removal' of the ammonia in order to try and keep the fish alive).

Of course no-one is going to fish in cycle like that, most will start with 2 or 3 fish. Now the chances are this tank WILL cycle quicker than the 'fishless cycle', but it's a bit like comparing apples to oranges, the 2 cycles are not equal.

2 or 3 fish (purely as an example), might only be 20% of your stocking level. Based on that and that above a 100% stocking produced 5ppm ammonia, this stocking level will produce perhaps 1ppm of ammonia.
So when this 'fish-in' cycle finishes it is able to cope with 1ppm of ammonia produced in a 24 hours period, so of course it will cycle faster than a fishless cycle that is trying to process 5ppm.

I guess if you wanted to really 'under-stock' your tank then you could fishless cycle with only 1ppm of ammonia, (and I think this would probably then still be quicker than the equivalent 'fish-in' cycle due to the frequent water changes required for fish-in as mentioned previously), but what is the point, you might as well do a full fishless cycle, have some patients, and then KNOW that you will be ok for up to 100% stocking level as soon as the cycle finishes.