'mature Tank' Vs 'cycled Tank'

[Schmill]

Ok, so sometimes my LFS (that isn't particularly 'L' ) asks me how long my tank has been running for etc before I buy fish.
I did at one time try to explain the whole fishless cycling to them, but I don't think they really grasped the concept (as many don't seem to) - lol

I'm just wondering what the actual difference would be between a 'mature' tank and a 'cycled' tank, (presume that the cycled tank has done a fishless cycle correctly etc etc etc).
An example is my cardinal tetras, when I bought them I was asked if my tank had been running for at least 4 weeks, which it had.

The reason I am raising this now is I am soon to start cycling my new tank, and it was my intention that once the cycling was compete I would just transfer my fish from my old tank to my new tank.

Just wondering if anyone can clarify for me whether there is any reason for needed to have a tank that has been 'running' for at least 4 weeks, and what they might be classing as 'running'. Are they just talking about 4 weeks of fish-in cycling, so my fishless cycle would actually be at exactly the same point, or is there more to it than that?

 

[Miss Wiggle]

theres a number of explanations for it, you can find a more in depth discussion of them here http/www.fishforums.net/index.php?showtopic=229642

my personal view is that in a new tank there are any number of chemical reactions going on between the substrates, decor, tank itself, equipment, water etc etc etc. we monitor a small number of levels (pH, ammonia, nitrite, nitrate, sometimes KH and GH as well) but there is a lot more than that in our water.

nature always strives towards an equilibrium so in the first few months things will be leaching all over the place and everything will be balancing out, after 6 months or so it all settles down.

now with delicate fish all this instability plays havoc with them and can easily make a fish poorly or kill it so you just need to wait for things to stabilise before adding them. Obviously it's not a dead set point where the day before 6 months they'll die instantly but the day after they'll be fine, just a general guideline of when the tank can be considered mature or stable.

there are other explanations such as the bio film developing over the tank and the bacteria colony being mature enough to double in 24hrs. The different views are not generally contradictory so I suspect it's most likely a combination of a number of factors.

 

[Schmill]

So all-in-all does that mean that even once my new tank is completely cycled and all is good with the world I still have to be careful which fish I transfer from my small tank into the new big one?

If so is there any advice based on my stock list below,

Many thanks!

Current Stock in the 60L Tank:

4 Albino Cory
4 Neon Tetra
2 Male Praecox (rainbow)
1 Female Praecox (rainbow)
1 Bulldog Pleco
1 Adult Female Guppy
1 Juv. Male Sword-Guppy type thing
+ half a dozen or so guppy fry that are currently floating in their baby pen in the 60L tank
+ plants (not the ones shown in my profile pic as most of those turned out to be non-aquatic! )

 

[OldMan47]

The guppies, swords, plants and pleco should all be good to go right away. I don't keep killies so I can't say about them. Neons can be a bit sensitive so I would hold back moving them until the tank matures a bit.

 

[Schmill]

Killies?

 

[OldMan47]

Sorry, Praecox.

 

[Schmill]

Sorry, Praecox.

Ah ok, was that a typo or is it an alternative name?

 

[ChilliPepper]

Killies are a different type of fish [URL="http/www.killi.co.uk/"]http/www.killi.co.uk/[/URL]

 

[Corleone]

Sorry, Praecox.

Ah ok, was that a typo or is it an alternative name?

It's the scientific name, Melanotaenia praecox. Common name is dwarf neon rainbowfish.

As grumpygourami posted, Killifish are an unrelated family.