How to acclimate new fish?

reg_pnw7(WA 7, sunset 4)July 5, 2007

What is the best way to acclimate new fish to the water chemistry of their new home?

When I started out with freshwater tropicals, many years ago in the day of independent fish stores, I was told to:

float the bag with the new fish in the tank for 15 minutes to equalize the temperature.

Then, open the bag, let in some tank water, close it up again, and let it float for another 15 minutes to acclimate the fish to the new chemistry, like the pH.

Then let the fish out.

But, is that adequate? Too many of my new fish refuse to eat right from the start and die within a couple-three weeks. I may not be acclimating them enough at the start.

What do you all do to acclimate new fish?

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woeisme(z7b NC)

This was discussed about a week ago in another post. Here is a link to the method I use. Makes alot of sense, and works fine. Unless dealing with "special" or "delicate" fish, this is pretty good for almost all fish.
Or, even easier. Use an appropriate sized container like an iced tea pitcher for example.

  1. empty the fish and water from the bag into the container.
  2. add some water from the aquarium (qt tank, all new fish should be QT'ed at least a month 2 or more is ideal). For the most part a 1 gallon jug is used, I use a 1 cup (8oz) container to transfer water from the aquarium to the container.
  3. after 10 minutes remove 1 cup of water from the fish container and add the same amount from the aquarium.
  4. continue this process up to an hour, or more. Pour the container and fish into an appropriate sized net. I like to use a brine shrimp or fry type material net for this. Once fish is netted, introduce it to the new tank.

I agree with the author that TDS is more important then temp. and pH.

Here is a link that might be useful: Acclimating fish properly

    Bookmark   July 5, 2007 at 10:03PM
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That's an interesting article, and while it does go along with our previous agreement of slow acclimation, it also, as you wrote; stresses the TDS factor, which is not always easy to ascertain in advance.

I never thought of using a salt water meter to test for TDS, although I have one, as I hatch BS, but now don't need to, as a battery powered digital TDS dip meter came with my new RO unit.

I guess I'd better start trying it out, to make sure I know how to use it, because I just placed an order for fish that will be shipped in next week.

But note that in the article, the author also writes that if the TDS is equal from bag to QT, the fish should be netted directly from the bag and into the tank, without our slow water changes.

However, regardless of any other factor: if the fish are alive and swimming in the bag water, releasing them into a small container long enough to be able to test the water shouldn't harm them. At least they are getting oxygen.

    Bookmark   July 6, 2007 at 10:21AM
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woeisme(z7b NC)

To be quite honest I don't use the article's method, unless it is a delicate or sick fish. If I am not mistaken, the author of the article doesn't do it all the time as he directs. I guess it is the "proper" way to do it. That doesn't mean the easier method, the one I use 99 44/100% of the time, risks the life of the fish. The float and dump method has been used for decades, I have never really heard anyone say that there fish where dying soley because of acclimation. Most pet stores still use the float and dump method when they get shippments. adjusting TDS can be real chore for the average fishkeeper, not to mention the expert. Unless you have virtully nutrient free and soft acidic to neutral pH water, without the luxury of RO/DI or CO2 injection, lowering pH and removing heavy metals can be a headache if not impossible.

    Bookmark   July 6, 2007 at 12:23PM
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When I worked for a tropical fish wholesaler and we received new fish, I was taught to empty the individual bags into a plastic cat tray. Placing an airstone in there was helpful. And as described above, I would add a little of the intended tankwater to the tray. Wait 15 minutes of so and add more tankwater. Empty some of that water in the drain and repeat the process. After a few add and drains the fish were released into the tanks or the inetr-connected system. It worked. Freshwater were floated for awhile in their new tanks and medicated first and their water from the bags were passed through a net first, before releasing. Catfish had to be treated more delicately, due to their hard and sharp fins.

    Bookmark   July 9, 2007 at 6:45PM
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