The "acclimation evolution..."

Ever notice how some techniques in aquarium keeping have evolved signficantly over the years? Although the basic goals of our evolving techniques usually remain the same, the nuances and ideas behind them evolve as new knowledge becomes available.

Some of the best examples of the idea of "evolved technique" are the approaches that we has hobbyists and industry types take to acclimating newly-received fishes to our aquariums. The idea has always been essentially the same: Get the newly-received fishes out of their shipping bags and acclimated to your aquarium conditions as quickly and stress-free as possible.


However, the approaches that we have used have evolved significantly from the "floating bag" technique of the 1960's, which was THE defect way to acclimate fishes at the hobby level for many years.

For the longest time, I was a "drip acclimation" kind of guy.

When I'd receive new fishes and inverts, it was all about floating the fish bag to equalize temperature, opening the bag, and dripping water from my quarantine tank over the course of 2 or 3 hours before ultimately removing the fish from the bag, discarding the water, and placing the fish in my quarantine tank. I still like it when bringing in fishes from friends or the LFS, with "time in bags" for the fishes of less than an hour.

Then, I was really into the "bucket acclimation" thing for years.

You  know, opening up the bag, dumping like  25% of the water in the bag out, then replacing with na equal amount of water from my quarantine tank... waiting like another 10-15 minutes and dumping half of the water in the bag, and replacing it with water from my quarantine tank again, then waiting another 10 minutes and netting the fish out and placing them in the quarantine tank, discarding the water in the bag.

About the only thing I have never varied is the use of a quarantine tank. It's a small investment that simply makes tons of sense. It's been re-hased so many times here and elsewhere that it's not necessary for me to talk about it again, but suffice it to say, it's a damn good idea to have one.

Lately, with fishes I receive via express services or mail, which might have been in the bag a day or two (or more), I've been embracing the "get them the hell out of the shipping bag ASAP" technique. Yeah, what we used to jokingly call "crash acclimation!" This sort of technique has been advocated for some time by Rachel O'Leary, whom I hold in very high regard as someone who's handled thousands of fishes which arrived after long journeys, and really "gets it" when it comes to their needs.

It makes a lot of sense.

The theory is that typically, the water in the shipping bag is a bit cooler than what you'll be using in your aquarium, and the metabolic rate of the fishes in the bag has dropped a bit during transit. Even thought they're essentially swimming in a bag of their own metabolic wastes, it's largely non-toxic, because the low pH in the bag keeps ammonia in the less toxic form of ammonium.


When we start floating the bag in a tank with water of a warmer temperature, the fishes' metabolism increases significantly, thus making them produce more CO2 and metabolic waste...Then, when you open the bag, the increase in oxygen increases thee pH significantly, converting the previously non-toxic ammonium into ammonia, which is, of course, decidedly toxic to fishes! And of course, the longer the fishes are in this opened bag of shipping water, the longer they are exposed to the "burning" of ammonia, causing a lot of stress at the least, and potentially fatal results at worst.

So, the idea is to open the bag, get some water conditioner( like Novaqua or Prime) in the bag (a few drops) to detoxify the ammonia. From there, I will usually just get the fish into the quarantine right away, the theory being that it's less stressful on the fish to acclimate to new water conditions quickly than it is to remain in a bag with increasing ammonia levels.

"The lesser of two evils", as they say!

I've personally never lost a fish from this process- and I receive a lot of fishes via express services and mail.

Of course, from this point, once you've detoxified the ammonia, you can certainly use drip acclimation or the good old "bucket method" and go from there if you want. With delicate fishes, or fishes from special water conditions, it can be sort of a toss up. Ask 5 hobbyists, you're likely to receive 5 different answers!

All of these techniques work.

However, it's situation specific, and you need to be able to utilize the technique that makes most sense in your specific situation, evaluating the pros, cons, and potential risks of each.

We used to do a low pH acclimation for newly received marine fishes at Unique Corals- a sort of "hack", which allowed for more trouble-free drip acclimation, keeping the ammonia bound up as ammonium as long as possible, while still "refreshing" the water in the shipping bags.  Of course, then you'd eventually expose the fishes to a "normal" pH once they are added to their holding tanks, creating some form of stress. However, the idea is that the stress of acclimating to different pH is far less damaging than leaving them in a bag of their own metabolic wastes and ammonia.

Is there a "perfect" acclimation solution?

Likely not.

They all involve SOME form of risk and potential challenge/stress to the fishes involved. It's part of the game. And there are all sorts of variations and twists and turns with each technique, too. And advocates and detractors of each. Yet, one of the things I've found over the years is that it makes sense to be both flexible and calm when acclimating fishes. It's a fun time, and shouldn't create excess anxiety or stress for you- or for the fishes, when possible. Adaptability to the situation at hand is only one aspect of being a good "acclimator!"

And seeing the evolution of acclimation technique over the years has reminded me that we should always remember that there are many approaches to the same problem, and that we have greater knowledge of the effects of shipping stress and how to combat them than ever before.

And no doubt, they will continue to evolve, as we continue to work with more scarce and demanding fishes from more specialized habitats and ecological niches.

Be open-minded to different aquarium techniques of all sorts; see the logic behind them. And never be too close-minded to changes or tactics that tilt the odds in favor of your fishes...Employ variations and nuances from a variety of approaches, particularly when they create greater probabilities of good outcomes! 

Stay open-minded. Stay educated. Stay innovative. Stay flexible.

And Stay Wet.

(Oh, and buy your fishes from Tannin Live!)  :)


Scott Fellman

Tannin Aquaitcs  




Scott Fellman
Scott Fellman


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