Adding Bag Water To Tank When Adding New Fish

[Meeresstille]

Hypothetically, when adding new fish to the tank, the general recommendation is to avoid getting tank water into the tank. The reasons being that diseases and parasites could be floating in the LFS' bagged water.
 
Then there is the ammonia build-up during the trip from the LFS to home, as well as the possibility that the fish could shed their protective slime coat due to the stress from being caught, bagged and transported, which could introduce toxins into the tank (or so I've read somewhere). 
 
Recently I've come across other school's of thought where the argumentation is that whatever is in the bagged water is also on the fish and therefor netting the fish won't make a difference, you can add the LFS' water. 
 
I'm only looking for an unemotional discussion. I'm curious as to how you handle this issue and your reasoning behind it. 
Thank you for your interest! 
 
 
 

 

[Install]

I wouldn't put too much thought into what literally amounts to a small amount of water. I don't put 'bag water' into my aquarium, one could argue that it contains all the 'panic chemicals' that you mention, or that the LFS's water might actually be in better condition, or somewhat similar to your own tank. To say there are 'schools of thought' on the matter seems a bit much, then again I could be wrong.

 

[Ch4rlie]

Interesting theory.
 
But I still would not want to add any LFS water to my tank, even though whatever is in the water is also on the fish, much less chance of spreading anything to original stocking if no LFS water is added.
 
Another reason for QT new stock before adding to main tank perhaps.

 

[Meeresstille]

Thank you for your replies, Install and Ch4rlie. 
 
I totally agree with the benefits of QT-ing new fish!
Sorry, the "school of thought" thing was just a figure of speech! 

 I probably should have said: "another way of thinking"!?

 

[l_l_l]

How long would one need to QT the fish then?

 

[PrairieSunflower]

For me, it has always seemed to have come down to the fish I bought and where they came from that caused the problem and not the bag water.  I go both ways with adding the bag water, sometimes I do, sometimes I don't... also depends on if I have fish already in the tank or not.

 

[Meeresstille]

How long would one need to QT the fish then?

Best is 4-6 weeks. It can take sometimes a while for infections such as callamanus worms to show.

For me, it has always seemed to have come down to the fish I bought and where they came from that caused the problem and not the bag water.  I go both ways with adding the bag water, sometimes I do, sometimes I don't... also depends on if I have fish already in the tank or not.

So the reason is you feel safe adding the bag water if you trust the source? (I've done that a few times too )

 

[PrairieSunflower]

Yes, I also figure if something bad is going to come the fish will have it stewing in them already anyway.
 
Also for quarantine... I find often once I hit 5 weeks that is the week something happens... so I'd definitely lean more towards the 6 week mark.

 

[CrimsonBoli]

I think its common sense. You selecting these fish from a display tank, so hopefully your choosing from a clean tank with no dead fish/illness/weirdness. And also choosing healthy looking fish!
 
Theres an argument to be had about whether its best for 25 display tanks to use their own individual filter or have them all linked up to 1 giant sump. (depending on fish etc...) as the giant sump method has the potential to mix all sorts of nastys around the other tanks, but a sump will be a better filter overall...
 
Personally I have always put the 'bag' water into the tank, and so far so good (adding fish this weekend so now I have jinxed it)

 

[l_l_l]

I would say that I usually do both. When I trust the source. All in. When I don't, no bag water.

 

[eaglesaquarium]

There's a LOT of stuff that will be in the water, that doesn't need to be added and certainly are things that you don't want to add to your tank:
 
 
List of things (incomplete);
 

• Ammonia - sure your filter bacteria should be able to handle it eventually, but why add extra toxins to your tank unnecessarily?
• Parasites - ich, as an example - the free swimmers could (and probably would) be available in the bag... why add extra parasites?  What's on the fish is bad enough, why add more than absolutely necessary?
• Poop - yup... the fish will poop in the bag, and why would you want to add that to the tank?  You'll just need to suck it out again during your next siphon.
• Fish species specific toxins...  corydoras excrete toxins under stress.  This toxin may not be high enough to actually be fatal to the fish in the bag, but again, why would you want to add a toxin to your tank unnecessarily?

 
Long story short, the potential hazards far outweigh the potential benefits... so I think there's really no reason to take a chance.  Its not hard to avoid the danger, so why not just keep the water from the bag out of the tank?
 
 
As pointed out, the best solution is to use a QT, but even then... its still best practice not to add water from the bag even to the QT.

 

[Donya]

In addition to all of the things Eagles listed, medications are an additional consideration when the home tank has inverts or very sensitive fish. Even if the LFS tank hasn't been treated recently, some chemicals can be absorbed by rocks/sealant during treatment and then be released slowly over time in amounts high enough to still harm certain animals.

 

[Meeresstille]

Thank you all for your replies. I kind of thought that the responses will be in those directions. Thank you eaglesaquarium and Donya for adding more reasons, the possibility of medications and the effects they could have on inverts is an awesome point!  
 
You were kind enough to humour me, so I'll be honest with you as to my (selfish) motivation. I had signed up on a German Animal Forum a few of months ago to improve my language skills. On that forum, recently someone had posted a problem with a newly added fish. Also, this person was obviously new to the hobby and since previous posters there had not mentioned it, I asked if they had allowed the bag water into the tank. I mentioned the problem with adding water from the bag, and the risks that can come with it. 
 
I was totally surprised by what came next. My recommendation was not well received. Well, different countries, different methods I guess... 
 
That's why I started this thread to re-confirm what I have learned in the last couple of years from you, the English speaking aquarists. 
 
Thank you so much, everyone, this was very interesting and helpful!  

 

[l_l_l]

It's true that all places have their own methods, very interest indeed!

 

[Ch4rlie]

I was totally surprised by what came next. My recommendation was not well received. Well, different countries, different methods I guess... 
 
That's why I started this thread to re-confirm what I have learned in the last couple of years from you, the English speaking aquarists. 

 
Very interesting, I am always fascinated by any other culture's way of doing things and set ups and probably some of their steadfast rules or regimes may be completely different to what we do.
 
Intriguing though that your recommendations were not well received and seems they have their ways and methods just like us