Quarantine Tank Questions

[Hathaway]

So after suffering losses as a result of adding new fish, and despite the fact that room is scarce in my house, I've decided that a quarantine tank is a necessity. Not willing to go through that again if I can avoid it, and I don't want the worry when adding new fish - supposed to be a joyous occasion after all!
 
So I've looked about online and after reading a few things I've ordered a Clearseal 72 litre (2 foot) tank, along with a sponge filter, heater, thermometer and air pump. I'll be getting a few plastic plants and perhaps a flower pot for hiding in. Am I right in thinking that I can remove the sponge from the sponge filter and place it inside my canister filter to allow bacterial growth? How long would it take given my main tank is fully cycled? I'm guessing it won't take as long as the initial cycle took for my display tank. The sponge filter I bought was this one (http/www.amazon.co.uk/gp/product/B00LHY31OA?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00), but sponge filters, unlike usual internal/external filters, don't specify the maximum litres it can filter, so is this sufficient for my tank or do I need to purchase another?
It seems 2-4 weeks quarantine is the standard period before adding fish to the display tank, would everyone concur with that? Also some talk of treating the fish, one citing copper sulphate. Is that necessary even if the fish display no outward issues?
Another thing, is it possible that a fish can show no symptoms in a quarantine tank, even after 4 weeks, and yet still infect the display tank once placed inside? As in a carrier, is that a likely at all scenario?
 
Thank you.

 

[fluttermoth]

Yes, you can cycle your sponge filter by putting in in your main canister; most of us keep a spare sponge or two there It does take around a month/six weeks, depending on where in the filter you put it; in contact with old media works quickest; if it's in a separate tray on it's own it'll take longer.
 
As hospital/quarantine tanks aren't stocked as heavily as your main show/display tanks are, a little sponge filter is perfectly adequate; they hold a lot of bacteria for their size. You must test the water every day though, if you're using this method, as the bacterial colonies can die back a bit after being moved.
 
You should never treat fish unless they show symptoms of something; so-called 'preventative medicine' in fish is one of the big causes of disease resistance. I've never heard of using copper sulphate, although we used to use potassium permangante in the old days (seriously, don't do that!).
 
It's extremely unlikely that fish would carry anything for longer than a month without showing symptoms themselves, so a month in quarantine should be plenty, IMO.

 

[Byron]

I concur with fluttermoth, though I would suggest a longer quarantine period may be advisable, depending upon the source of the fish.
 
Five weeks, six better, and if there are no issues I would move fish over.  Sometimes a longer period is advisable if fish are delicate, difficult to feed, etc., as it is much easier in a QT to get such fish eating better.  There is no competition from other fish, plus you can "overload" the food a bit, as it is easier to clean up with water changes and substrate vacuuming more frequently if needed.
 
You are in the UK, but from a couple other current threads I think you may have much of the same problem now afflicting North America, and that is the level of "unseen" disease in commercially-raised hobby fish.  In my 20+ years in the hobby, all my serious fish disease losses have come in with "bread and butter" fish that have been commercially raised (as opposed to being wild caught) and in the past five years.  This is why I tend to avoid chain stores; these obviously get their fish from the same source, so disease is more likely to be widespread.  And the weakening of many of these now commercially-raised fish is likely part of the problem.
 
And it is true that fish can carry disease without ever themselves succumbing to it.  It is also true that there are internal protozoan pathogens that may be un-noticed for weeks, even months, before the fish suddenly dies from it.  I know of aquarists who will quarantine for 3-4 months minimum.  I suppose no one can be 100% safe, but it is still wise to take as much precaution as you can under the circumstances.  From 1983 until 2009, I never quarantined fish, and I had no issues (other than ich a couple times, which is relatively easy to deal with).  But three in a row cases of losing half a tank of fish from an invisible internal pathogen convinced me to change my procedures.  I also am very careful where I acquire fish; these cases all came from "common" hobby fish from chain stores.
 
And fluttermoth is quite correct in not treating fish unless they show signs of definite issues.  Aside from building resistances, we sometimes forget that every substance added to the tank water is getting inside the fish, via the gills or directly by osmosis through the cells and into the bloodstream and internal organs.  And some fish cannot tolerate certain chemicals or medications.  Stress is the direct cause of 95% of all fish disease; healthy fish not subjected to stress should be able to fight off most issues.  Pathogens from many diseases are constantly in our tanks, but only when stress weakens the fish do these pathogens manifest themselves.  This is why I don't recommend bare QT tanks; it is better to have a more natural environment, using decor as you mention.
 
Byron.