Aquarium and Pond Care with EcoBio-Block

Safely Transferring Fish to a New Aquarium

discus fishWhen you are ready to purchase your first aquarium, one of the first things you learn is how to properly cycle the aquarium and how to slowly introduce new fish to avoid ammonia spikes while the colonies of beneficial bacteria are developing. That’s easy enough to follow — but what about when you have to move an existing community of fish to a new home? Maybe you moved and have to re-establish the aquarium, maybe you’re moving to a larger or even a smaller tank; whatever the reason, there are ways to safely move the fish without as much risk of ammonia spikes.

A properly cycled tank contains a healthy colony of bacteria that breaks down ammonia from a fish’s waste and uneaten food into nitrites and then into nitrates. In a healthy tank, there should be 0 ammonia, 0 nitrites and less than 40ppm nitrates (20ppm if you have invertebrates such as snails or shrimp). Without sufficient amounts of beneficial bacteria, ammonia and nitrite in the water may be fatal to fish.

Beneficial bacteria live all through the water and on every underwater surface in the aquarium, but the water itself carries a very low concentration of bacteria so it’s not very effective to simply transfer water from the old aquarium to the new in order to maintain bacteria levels. Ideally, you will be able to transfer some old filter media to the new aquarium, or even a handful of gravel or fake plants that will all have beneficial bacteria on them. Make sure that the materials of your choice stay wet with tank water until they can be placed in the new aquarium.

Alternatively, if you have EcoBio-Stone products in your aquarium, that will be sufficient to switch over to the new one. EcoBio-Block has a lot of beneficial bacteria living in its volcanic rock and has quite a bit of surface area so a lot of additional bacteria get transferred over from the established tank. It is not necessary to keep EcoBio-Block wet, but it may help eliminate any minor ammonia spikes that may occur after the transfer as there will be more active bacteria immediately if kept wet. EcoBio-Block will also allow you to wait a little bit longer before doing the first water change as it provides essential minerals that would otherwise have to be replenished through water changes, giving the fish extra time to de-stress after a big move without being bothered.

Make sure not to put whatever bacteria-containing materials you’ve chosen into the new aquarium until a de-chlorinator has been used in the water as chlorine will kill the bacteria. Keep close tabs on the water parameters for the first week after the transfer, doing minor water changes as needed to compensate for any ammonia in the system that may not be compensated for by the bacteria yet. Watch the fish closely for any clamped fins or red, puffy gills as these may be signs that the water parameters are off. If these simple guidelines are followed your fish should have a relatively effortless and healthy move.


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November 3, 2008 at 1:37 PM
  • February 5, 2009 at 11:16 AMJean

    I want to transfer my fish from 29 gallon tank to 40 gallon tank. The 40 gallon tank currently has a 5″ pleco, which I intend to keep, and a 5 inch African Cichlid I will be giving away. Do I need to start new with the 40 gallon tank? Empty all water?

  • February 5, 2009 at 12:42 PMArline

    Hi Jean,
    You shouldn’t start over again. Its a big shock to the fish’s system if its suddenly transferred to a completely different environment. You will have to check to see if the pH and the temperature are about the same in both tanks. If the temperature is not the same, you can put the fish that you are transferring in water from the old tank and stick them in a plastic bag and float it unopened for 30 minutes in the new tank. Then open the bag, rolling down the sides and let it sit in the water. Change 1/4 of the water in the bag with water in the new tank every 10 minutes for a half hour. That lets the temperature and pH change slowly.
    When you do put the fish in the tank, feed the old fish first so that it won’t attack the newcomer and turn off the aquarium lights to reduce stress.

  • June 7, 2010 at 6:33 AMrobinsingh

    i want to know it is nessesary change accurium full water ………n how many days we change fish tank water ,,,,,

  • June 8, 2010 at 9:44 PMAquarium Care

    You should never change the entire water in the aquarium. It will stress the fish. Depending on the condition of the tank, under normal circumstances you would change about 20 – 30% of the water every two weeks. If you have EcoBio-Block, you would not have to change the water so much. Just test it and monitor the water to make sure that it stays clear and healthy for your fish.

  • July 8, 2010 at 5:26 PMmary sines

    switching from 40gal to 75 gal tank,with fish,whats the best way to do this?

  • July 8, 2010 at 8:47 PMAquarium Care

    Put some gravel and filter media of the 45 gallon tank into the 75 gallon tank and add de-chlorinated water. Its a big shock to the fish’s system if its suddenly transferred to a completely different environment. Check to see if the pH and the temperature are about the same in both tanks. If the temperature is not the same, you can put the fish that you are transferring in water from the old tank and stick them in a plastic bag and float it unopened for 30 minutes in the new tank. Then open the bag, rolling down the sides and let it sit in the water. Change 1/4 of the water in the bag with water in the new tank every 10 minutes for a half hour. That lets the temperature and pH change slowly.
    Turn off the aquarium lights to reduce stress. At this point, your new tank is going to cycle again and if you use EcoBio-Block (I recommend the Stone L), you can speed up the cycle and reduce the need for future water changes. Just be sure to monitor the levels in your tank.

  • September 6, 2011 at 9:44 AMrussell b

    I got a new tank 55 gal and I put two large fancy gold fish in them to help jump start the cycle of the new tank is what I did harmful to the fish and tank.

  • November 26, 2011 at 12:48 PML. Silas

    One of my neighbors have to move. He has a 55 gallon tank. Im the new owner. I want to transfer my fish to the big Tank. Is there anything special I need todo first?


    L. Silas

  • November 29, 2011 at 10:53 AMAquarium Care

    If you have gravel, move some of the gravel and your filter media to the new tank. You are basically starting a new tank, your tank will have to go through the cycling process. Don’t add all fish at a one time if possible. For a 55 gallon tank, EcoBio-Stone M (or L if you have a lot of fish) will speed up the cycling process and keep your tank clear, clean and healthy for about 2 years. Monitor your ammonia and nitrite levels and change about 20% of your water about once a week, until you finish cycles. After that, you can change water less often, just continue to monitor your chemical levels.

  • January 1, 2012 at 12:00 PMColleen

    I want to transfer my oscar to a 55gal from a 30gal, I will be transferring the biowheel filtration along with it and was wondering if i need to worry about the tank cycling again with just adding more water? Also, can I use saltwater T5 lights on a freshwater aquarium?

  • January 1, 2012 at 10:15 PMAquarium Care

    It’s possible that your tank may go through a mini cycle, because you will have nearly double the water amount.
    Yes, you can use the saltwater T5 lights in your freshwater aquarium.

  • March 11, 2012 at 4:40 AMTimothy

    Hi, I got a 40 gallon tank and now i want to move up to 55 gallon, can I just transfer the water from old tank to new. Sorry I Don’t have to wait for cycle of a new tank? This is freshwater.

  • March 11, 2012 at 4:41 AMTimothy

    I mean so **** not sorry.

  • March 13, 2012 at 8:46 PMAquarium Care

    To help avoid new tank syndrome, you should move some of your gravel and your filter media to the new tank. You can then transfer some of the water from your old tank (you don’t have to transfer all of it). That will keep your pH levels from changing. Move your fish as you would if you were bringing them home from the store. Place in a plastic bag with water from the old tank. Place the bag in the water gently for about an hour and then slowly release the fish into the water. If you use an EcoBio-Block, (recommended size the EcoBio-Stone L), you will keep your fish tank clear, clean and healthy for your fish for up to 2 years.

  • April 3, 2012 at 12:31 PMSamuel Mclean


    I would say im a fairly experienced fish keeper, however, I’ve never had to switch tanks. Infact, I have, and was very unsuccesful leaving all but 2 hardy white cloud minnows (which I still have now).

    My current tank has been running for 1.5 years and looking to change from the current 48 litre to a 60 litre tank.

    Was wondering, if I transferred all 48 litres to the 60 litre tank adding NO fresh water yet, and also transferring the current plantation ornaments, if this would be sufficient for the fish to survive?

    Additionally, would it be neccesary to keep the old filter running in the new tank for a short duration?

    Thanks in advance!

  • April 3, 2012 at 5:59 PMAquarium Care

    Yes, you can transfer the water from the 48 litre tank to the 60 litre tank plus if you have gravel, you should move as much as you can of that as well. You definitely should use the old filter in the new tank as it holds a lot of the beneficial bacteria which is what makes your tank’s cycle finish quickly.
    If you use EcoBio-Block, you can help increase the activity of your bacteria and keep your tank clear, clean and healthy.

  • April 3, 2012 at 9:11 PMSamuel Mclean

    Many thanks!

    Really appreciate the help


  • May 15, 2012 at 8:47 AMJosh

    hello i am wanting to switch tanks. im currently using a 29 gallon and i have a 25 gallon tall. if i put everything from my old tank to my new tank do i have to do anything extra. will it be ok.

  • May 16, 2012 at 5:08 PMAquarium Care

    There should be no problem transferring what you have in your 29 gallon tank to an 25 gallon one. Of course, if you have EcoBio-Block you will reduce your maintenance and your fish will enjoy clear, clean, healthy water!

  • July 14, 2012 at 1:39 AMmike

    I have 2 cichlids from lake malawai in a 10 gal tank.One of which is quite lathargic and getting picked on.I have my main tank which is 55gal and all fish in that tank are fine.Should I move the lathargic one or the aggressor or both to 55 gal tank and can I just put them in a bucket and net them into 55gal tank.My 10 gal tank the nitrates have been high and I have been doing water changes quite frequently.

  • July 15, 2012 at 7:31 PMAquarium Care

    Cichlids should be kept in their own tank. If one of them is lethargic, the aggressive one will attack the other one. Cichlids need lots of room, generally about 30 gallons for one or two of them. They are best kept as singles or if breeding, should be in a large tank. The firemouth cichlid and the rainbow cichlid can usually be kept in a community of fish, but most of the other cichlids are too aggressive for most community fish. If you let us know what kind of cichlids and what kind of community fish you have, we can tell you better.

  • July 29, 2012 at 6:53 AMchris

    Im replacing my 55 with a 75 and having some problems. I first installed a 3d background using ge silcone1, then waited about 48 hours to fill tank, I used my hose from a spicket outside. I let the hose run for a few minutes then proceeded to filling the tank. When I was done I plugged in all my new filters and noticed that a rust colored almost film on the bottom of the tank glass and some were in clusters. I then added chlorine chloramine remover,aquarium salt,ph and biofilter to it. then i noticed 1 of my cichlids was sick in the established 55 laying on the bottom breathing heavy it looked like parasite so i medicated the tank with quick cure for ick/protozoan parasites raise temp to 87 added aquarium salt. after just a few hours i could tell he was to far gone for a recovery. scared of transfering disease to new tank i medicated it as well. let it run for another 2 days and still noticed the rust film and clusters on bottom. filled all previous tanks with the same hose from same water so i just wiped off with a new filter pad and added pool filter sand, all decor from 55 to 75 added more ph gave it an hour water test perfect temp good added 1 fish watched him for about 30 min he started coloring up real nice fed him but when he didnt eat i was worried, watched him lay down in the sand, got him out of there put him back in 55 really dont know whats going on for him to lay down like that maybe the chemicals not mixing together or the rust HELP got a 220$ order coming fri got pregnant cichlids and sick cichlids

  • July 29, 2012 at 9:12 PMAquarium Care

    A few things on this one —
    1) Raising the temperature and adding salt is the WORST thing to do, as it
    stresses fish that are already stressed. Plus adding anything without really
    knowing what you’re treating for is probably a bad idea.
    2) Unless you are sure that the GE silicone was ok for tanks, it may have
    other chemicals in it
    3)The worst thing is the “rust”. When you can actually see rust in a
    film and clusters that is where you should have stopped. That water from the
    outside spigot should not be used in an aquarium. You need a water source that isn’t contaminated.

  • January 14, 2013 at 9:00 PMNhi

    I have a new 26 U.S. gallon tank and recently added 2 discus fish a couple days ago. However they have started to show signs of stress, so I bought a new heater to make the water warmer because the heater that was in the tank originally would not get warm enough. I was wondering if it was okay to switch the heaters while the discus fish is still in the tank, because I know it will take the new heater some time to warm up and will the cool water kill the fish?
    I hope that made sense :S

  • January 15, 2013 at 10:55 PMAquarium Care

    You could use both of the heaters until you reach the proper temperature and then take the old one out.

  • February 18, 2013 at 9:16 PMSalty newbie

    I have a 125 fowlr for 7 months, it’s doing great. i have a 206 and a (i think) 405 filter on it. my husband decided to get me a lionfish which wouldn’t be compatible with the fish I have. It’s currently in the quarantine tank. So I set up my old 110g tank, put in base rock and a few live rock and put my 206 filter from my 125g tank on it for the bio ‘factor’. How long do you think I would have to wait to put my lionfish in there?

  • February 18, 2013 at 11:09 PMAquarium Care

    Usually marine tank should cycle within six to eight weeks. Just check ammonia and nitrite levels every 2 to 3 days to make sure the ammonia concentration doesn’t reach above 0.5 mg/l and nitrite above 1.0 mg/l.

  • April 6, 2013 at 5:53 AMJnut

    Hello I have a few cory catfish and a couple algae eaters in a 10 gallon tank which I’m upgrading to a 40 gallon. I have the 40 gallon set up and have transferred a few of the old decoration and put some of the old gravel in a stocking and placed it in there as well. I also used some quick start, I plan to transfer the old filter as well for a few weeks. My question is when can I tranfer my fish to the 40 gallon and should I transfer the old water and when should I transfer the filter? I really need help with this cause its really stressing me. Also I put about 10 gallons of RO water along with tap water in the 40 gallon and I have another 5 gallons in a bucket just in case, if that makes any difference. Thanks in advance

  • April 6, 2013 at 11:02 AMAquarium Care

    You can transfer your fish when the ammonia and nitrite levels are zero or very low. If you want to hurry the process along and keep your water clear, clean and healthy, the addition of an EcoBio-Stone M will speed up the process, and reduce your need for water changes and maintenance for a couple of years at time.

  • May 2, 2013 at 3:21 AMDannii

    I have 5 goldfish (Black Moor, 2 Shubunkins, 1 Comet, 1 Pompom) in a 40L tank that they have out grown. I have recently purchased a 200L tank and a filter full of bacterial goodness was emptied into it. I let the filter run for 5 days before adding a store-bought fish just to see what would happen. I took a water sample into the store to see if it was ok but the lady said it wasn’t worth testing as it probably wouldn’t have cycled.
    How long before I should take the water to be tested?
    If the results are ok, how long should I wait before transferring my fish over?
    Should I put some of the water from their current tank into the new tank?
    I have already put ornaments from the old tank into the new tank.

    PS – the store-bought fish in the new tank seems to be coping well. He is active and eating and there are no obvious signs of stress.

  • May 9, 2013 at 10:04 AMAquarium Care

    Sorry for the delay in responding to your post. It went to our spam folder and we just found it.
    You don’t need to take the water in to the store to be tested. It’s better if you test it yourself and at this point you should be testing it every few days and you can put in the other fish once your ammonia and nitrite levels are almost zero. I’m surprised that the lady at the store said it wasn’t worth testing.
    It is a good idea to put some of the water from the current tank into the new one when you transfer the fish. Also, make sure that the temperature and the pH for both tanks are about the same.
    If you want to speed up the cycling time and keep your water clear and healthy, EcoBio-Block is a great addition to any tank.

  • July 28, 2013 at 4:40 PMchristine

    Hi, I have a variatus platy in a 13 litre tank, she gave birth 5 weeks ago to 18 babies, and today she has given birth to another 10, the babies have been in a hatchery in the same tank since birth. I have recently purchased a 7 litre tank that I want to transfer the babies over to as there is now too many in the hatchery and I am worried they are not getting enough food and that is is taking them longer to grow.
    Please can you advise me on the best way to do this?

  • July 28, 2013 at 8:33 PMAquarium Care

    You should put some of the water and some of the gravel and filter media from the old tank into the new one and wait until the nitrogen cycle is completed. Also, make sure that the temperature and pH are the same as the old tank. After that, it should be safe to move all the babies to the nursery tank. Of course, EcoBio-Block is always a great addition as it will keep your tank clear, clean and healthy for the babies.

  • August 2, 2013 at 8:23 PMNathan

    Hi, my guppy recently gave birth to over 30 babies and its getting really cramped in the breeder box. I heard that they also stunt your babies growth so I wanted to transfer my fry over to a little 5 gallon tank that I had setup 2 days ago. I’m using a small old filter that was still a bit dirty from previous usage and I put in a new filter cartridge. I also put in some plants from the community tank, but the water is new. The conditioner is already put in and so are the beneficial bacteria solution. I don’t have a water sampler so I do not know if the cycle is complete. The filter has been running for 2 days now so Is it safe to put in the fry?

  • August 4, 2013 at 8:05 PMAquarium Care

    Well, the problem is that the water probably hasn’t cycled. You need to check your water. You should get a test kit from your pet store for ammonia, nitrite, and nitrates. Once the water has cycled, it will be safe to transfer your guppies.

  • September 21, 2013 at 9:15 PMAllen Tower

    Hello I currently have a 10 gallon tank with 4 Zebras, 2 gupys and a 1 small Green spotted puffer and my ten gallon as a slow leak and I need to move them to my new 29 gallon tank. What Should I do move all the gravel over and the filter with the media to the new 29 and transfer the fish? or do I have to wait a couple days before moving?

  • September 22, 2013 at 8:08 PMAquarium Care

    You can try putting your fish and the old water into a container with your air supply. Then put the gravel and the filter with the media in it into the new tank and add add water conditioner. Make sure the temperature of the water is the same as the water that your fish are in and after a couple of days,put them together with the water from the old tank in plastic bags and place them into the new tank, until the temperature is about the same and then slowly add water from the new tank into the plastic bag. Do this about 5 times. Let it sit for about 5 minutes each time, then slowly let the fish and the water out into the fish tank.

  • October 19, 2013 at 10:52 AMkyle

    Hi, I added 6 fish to my 55 gallon tank 3 days ago…. how long should I wait to add more fish if all my levels are good?

  • October 19, 2013 at 9:07 PMAquarium Care

    As long as your levels are good, you can add fish. Add a few at a time, wait a few days and check your levels and then if they are okay, you can add some more.

  • October 20, 2013 at 6:26 PMkyle

    Awesome, so I added some and they are doing great. I might add more in a couple days… thanks for the info!

  • October 20, 2013 at 7:33 PMAquarium Care

    You are so welcome! Anytime.

  • October 30, 2013 at 3:35 PMRachel

    Hi, we are ripping out the carpet in our living on the weekend and we have a 55g fishtank. How should we go about moving the fish? We obviously can’t leave them in there and carry the fish thank because it is way to heavy. Can I put them in a big bin while we do the flooring? How long can they stay in the bin without pumps?

  • October 30, 2013 at 4:12 PMAquarium Care

    Yes, you can put them in a big bin, but if you cannot keep them there for a long time. The best thing to do, although it is a lot of work is to siphon off most of the water from the tank into the bin (if you have plants a few plants would help keep them from stressing), gently put the fish in there and cover it with a loose lid. Then (keeping the tank as level as possible and avoid jarring), move the tank gently (you don’t want it to break or get loose at the seams) into another room and siphon back the water and return the fish. (Add water if necessary).
    We had a pump problem once and put the fish in big bins and kept putting water in, but we lost several fish after a day or so. so I would not leave them in water without an oxygen source for long. Our fish were really big, which was part of the problem. If your fish are smaller, they will probably not have as much of a problem.

  • August 12, 2014 at 3:24 PMDan

    I am upgrading my 55 gallon saltwater tank to a 90 gallon setup I want to add new sand to the 90 gallon tank but am afraid that will kill my fish when I add them because of the lack of bacteria how do I go about this process on doing everything

  • August 12, 2014 at 3:48 PMAquarium Care

    Keep a couple of cups of your old sand and mix it with the new. Put the sand, your EcoBio-Block and some of the water from your old tank, as well as some base rock into your new tank. You can use one of your live rocks to seed the base rock.

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