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How to Acclimate Freshwater Aquarium Fish to Your Tank

After setting up your new aquarium and going through the tedious process of cycling it, it can be very tempting to snag some pretty fish at the aquarium store and release them right away to finally get going. You did your waiting!

Unfortunately, fishkeeping really is a hobby for the patient. If you want your new pets to live long and happy lives, youโ€™ll have to wait a few more hours as they acclimate. Find out how that works below.

Why Is Acclimating Your Fish So Important?

Stability and patience are the two keys to keeping fish successfully. The need for the former is the reason we need to acclimate any new additions before introducing them into our tanks; the need to practice the latter is a direct result.

Neither fish nor invertebrates appreciate sudden changes in their environment. Not. At. All. Any swings in temperature, pH, hardness, nitrate level, and other parameters greatly stress them out, often leading to shock or even death. Unfortunately, the chances of a shopโ€™s water being identical to that in your tank are pretty much zilch.

As tempting as it may be to release new fish right away and see them swim freely in their new environment, youโ€™ll have to be patient for just a little longer. Spending a little more time in their bag or a bucket doesnโ€™t hurt the fish, and we can attest to much better results with careful acclimation than with the so-called โ€œplop โ€˜n dropโ€ method.

Tip: If youโ€™re adding fish to an aquarium with existing inhabitants, theyโ€™ll have to go into quarantine for 3โ€“4 weeks first to make sure they donโ€™t spread any diseases. This also means they have to pass through the acclimation process twice. Some aquarists even like to quarantine their first additions, as dosing medication is easier in a small quarantine container than a big display tank.

Acclimation Step 0: Planning

Acclimating your new fish starts before you even head out to the local aquarium store to buy them. After all, itโ€™s not just about giving them time to get used to the water parameters in your aquarium: youโ€™ll also have to make sure those parameters are in order in the first place. Impulse buying can end in heartbreak if your tank isnโ€™t actually ready to receive the fish.

There are a few different factors to consider when getting ready for new fish to arrive. First off, itโ€™s important to know exactly when youโ€™re going to buy or receive your stock. If youโ€™ve ordered online, make absolutely sure youโ€™ll be home when the package arrives. They donโ€™t like sitting out on the porch, especially when itโ€™s very hot or cold out!

Consider performing a water change the day before the fish come home. This gets rid of excess nitrates and any other built-up gunk. You definitely donโ€™t want to have to change water right after their arrival โ€” new fish need to be left alone as much as possible for the first few days.

We also recommend one last full water test panel, just to make absolutely sure the water is safe. If it isnโ€™t, thereโ€™s still time for last-minute measures like changing more water, borrowing some cycled filter media, or using an ammonia neutralizer. Scrambling to do any of those things when you just wanted to sit back and enjoy your new pets is no fun.

The Acclimation Process

Everything set? Youโ€™re now ready to go forth and purchase those fish. If you donโ€™t have one yet, we highly recommend also picking up a drip acclimation kit. Youโ€™re heading to the aquarium store anyway, and these kits totally beat acclimating with scoops of water or fiddling around with airline tube loops and rubber bands.

Try to make transport as stress-free as possible your new pets, especially if they have a long drive ahead of them. A lidded, insulated box to prevent temperature swings can help get them home safe.

Made it through the front door? Great, letโ€™s acclimate those fish and get them into your tank!

Drip Acclimating

Drip acclimation is by far the easiest and most stress-free way to acclimate new stock. All you need are a container โ€” the bucket you use for water changes should work fine โ€” and some airline tubing. A control nozzle for the tubing is ideal, but if you donโ€™t have a full drip acclimation kit, there is another way to control the flow.

Gently move the fish and the shop tank water into the bucket. Then, start the water flow through the airline tubing from your display aquarium to the container. This is similar to when you do a water change, except youโ€™re looking for a flow rate of just two drops or so a second.

Achieving the right flow rate is easy with a controllable nozzle, but it can also be done by folding over a piece of the tubing and fastening it with a rubber band. You might have more trouble perfecting the drip speed, but some fiddling usually gets you close enough. Just keep an eye on it โ€” the rate can slow down or speed up as the loop in the tubing settles.

And nowโ€ฆ you wait. Youโ€™ll want to roughly quadruple the amount of water in the container, which generally takes an hour or two. Check back regularly to see if all is well, but try not to disturb the fish too much.

Tip: Your fish or shrimp (or crayfish, as below!) will appreciate a little cover. An aquarium plant or even just some floating mesh work fine to help them feel safe.

Crayfish in acclimation container with aquarium plants

After Acclimating

Hopefully (and likely!) all of your fish will still be alive and kicking at this point, if a little stressed. Time to move them to their new home and then leave them alone so they can settle in. We recommend discarding the water in the acclimation container, as it contains shop water that can come with unwanted extras.

Finish the move by gently netting the fish and moving them into the display tank. Ignore the urge to feed them in an attempt to make them comfortable: itโ€™s more important for them to get some peace and quiet. This is why itโ€™s also a good idea to keep the tank lights turned off for now. You can still keep an eye on them by the ambient light.

Keep monitoring the fish after turning on the lights and feeding them tomorrow. Itโ€™s not unusual for them to ignore food or look skittish for a day or two as they settle in, but lethargy or trouble swimming could mean trouble. If you think something might have gone wrong, a water test can help figure you out whatโ€™s going on.

Skip the Stress

Feeling intimidated by all the steps necessary to get new fish from A to B without any casualties? Itโ€™s more work than one might expect!

Luckily, FantaSEA aquariums is here to take care of all aspects of setting up (and maintaining) your aquarium for you. All fish are quarantined to prevent disease and carefully acclimated to your tank by our knowledgeable staff. Sound good? Contact us today!