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  • Species: Myriophyllum mattogrossense

Acclimatising Your New Fish and Plants

10 July 2019

Acclimating Fish To Your Water Conditions

Whether you’re introducing fish to your main tank or a quarantine tank, the basic process should always be the same: expose the fish to as gradual a change in water chemistry as possible. A few fish have evolved to handle big changes in water chemistry (brackish water fishes, for example) but most react very badly to sudden changes in pH, hardness, salinity, and temperature. Whether the fish is going from worse to better water conditions is irrelevant here, so don’t assume the fish will be happy to get out of the dirty water in the bag and into a proper aquarium because it doesn’t work quite like that. Fish adapt over time to even bad conditions, and will need to re-adapt to the better conditions in your aquarium.

The traditional way to introduce new fish into the aquarium is to place the bag containing the new fish into the aquarium unopened and leave it floating for 20-30 minutes so that the temperature inside the bag matches that of the water in the aquarium. The bag can then be opened and the fish gently poured into the aquarium. The problem with this method is that while it eliminates the problems of temperature change, it does nothing about water chemistry. So a common solution is to use a needle to pierce the unopened bag half a dozen times while it is floating it in the tank. Water will diffuse in and out of the bag, gently changing the water chemistry inside the bag to that of the water in the aquarium. This approach can work very well, but the downside is that water from the bag gets into the aquarium, dumping the load of ammonium that accumulated while the fish was being transported and potentially allowing in any swimming parasites that were in the retailer’s tanks, such as whitespot.

A cleaner method is to half-fill a bucket with water from the aquarium and float the pierced bag in that. This will allow the fish to adapt to changes in water chemistry and temperature safely, while keeping the dirty water in the bag isolated from the aquarium itself. After acclimation, the fish can then be netted out and put in the aquarium, and the water in the bucket discarded.

Some aquatic organisms are more sensitive to water chemistry changes than others, and for the most delicate species, particularly marine fish and invertebrates, the "drip method" is particularly favoured. If you are shopping for fishes likely to need this technique, it’s a good idea to ask your retailer to pack them in an oversized bag with as much water as possible. This is because you will pour the contents of the bag -- water and livestock -- into a clean bucket, and if there isn’t enough water in there, the livestock may be exposed or unable to swim properly. If there isn’t enough water in the bag, use the pierced-bag technique to add the minimum amount of aquarium water to the bucket to safely cover the livestock. Either way, release the livestock into the bucket and discard the bag. The trick now is to drip in tiny amounts of water over a long period so that the water chemistry gradually changes over time. Airline tubing and plastic regulator valves work perfectly and are very inexpensive and can be easily bought at any aquarium shop. You’ll also need some type of attachment device to hold the tubing onto the tank; again, inexpensive clips and suckers can be purchased to do the job, or else DIY solutions using adhesive tape will work just as well. Either way, use the tubing as a siphon, placing the valve at the end to control the flow so that nothing more than a drip at a time comes out. When the water in the bucket has doubled, scoop out a cupful and throw it way, and then allow the level to rise again. Do this once or twice more. The whole process should probably take about an hour, and in that time the fishes or invertebrates will have slowly and safely acclimated to the new conditions. They can then be carefully removed from the bucket and put in the aquarium.

A word about moving fish and invertebrates. Most fishes are fine exposed to air for a short while, but pufferfish can pump themselves up with air and find themselves unable to deflate themselves properly, and many invertebrates, such as sponges and sea urchins will die if bubbles of air get trapped inside their bodies. When moving such delicate animals, scoop them out of the bucket using a suitably sized container that keeps them underwater at all times. A clean jam jar or ice cream carton is ideal for this. Using plastic or glass containers instead of nets also works very well with spiny fish such as catfish that tend to get tangled up in nets. Damage to the skin following attempts to untangle them can make them vulnerable to fungal and bacterial infections. Also bear in mind that some fish and invertebrates have stings, so when transporting them, take special care to avoid touching them. Among the species known to have stings are lionfish, stonefish, waspfish, scats, numerous catfish, some sea urchins, and certain corals. Surgeonfish and spiny eels aren’t venomous but they are equipped with sharp spines they will readily use when stressed, so handle them with care as well.

Moving Plants Into Your Aquarium

On the whole plants tolerate changes in water chemistry very well, but almost always being uprooted causes some degree of shock, and most plants will shed a few leaves after they are planted in your aquarium. It usually takes a few weeks for plants to settle down, but assuming the conditions are within their range of tolerances, most plants recover from the ordeal of being uprooted and transplanted without problems. The chief exceptions are among the marine algae: most need to be acclimated to a new aquarium in the same way as delicate marine invertebrates, using the drip method. Further exceptions are among the mangroves. While most mangrove propagules ("pods") can be transported easily between fresh, brackish, or salt water conditions, once the propagule has developed leaves or roots it must be kept at whatever water conditions it was germinated under, so a salt water adapted mangrove plant can’t be added to a brackish water vivarium, or vice versa.