# How to reintroduce fish back to tank



## Jodienathan212 (Jun 9, 2014)

1. 36 gallon bowfront tank and ten gallon hospital tank

2. three rosy red minnows (feeder fish); two white cloud mountain minnows

3. 36gallon tank has been running with fish approximately 5 months

4. one of the rosy reds has been in tank for 5 months, two in tank for one month; white cloud mountain minnows in tank for 4 months and recently transferred to ten gallon tank.

5. rosy red minnow started hiding after one minnow was found on floor and other seemed to have disappeared? (may have jumped out of tank and been eaten by cat? I have since covered tank with screen); he was all alone for about a week before I purchased two more rosy red minnows. After purchasing the two additional rosy reds, ten of my white cloud mountain minnows started to get sick and die over night (one died each night) leaving me with a total of two white cloud mountain minnows who have been transferred to a hospital tank and medicated with Kanamycin and Furan 2. 
Before the white clouds died they appeared to stop swimming and the lower half of body would sort of droop. I thought maybe a couple also had a white cottony mouth.
What I find strange is that the rosy red minnows in the 36 gallon tank were and still are perfectly fine, while the majority of the white clouds got sick and died.
The two white clouds who have been transferred to a hospital tank appear be okay now, they are eating and swimming around. I treated them every other day with a total of three doses of kanamycin and furan 2.
My question is how do I go about adding the two surviving white clouds back to the 36 gallon tank. I am concerned something in the tank made them sick, however I do not know how to go about treating the 36 gallon tank; especially since the three feeder fish (rosy reds) in it appear to be fine. What I may do is put the white clouds in a 5 gallon, and the rosy reds in the ten gallon so that I can treat the 36 gallon tank.
How do I treat the 36 gallon tank? and should i treat the three rosy reds even though they appear to be fine; to make sure they don't give anything to the white clouds?

I am using a AquaClear 50 Aquarium Power Filter in the 36 gallon bowfront, and a Aqueon quietflow internal power filter in the ten gallon hospital tank.

I change about 1/3 the water in the bowfront once per week and use the API freshwater master test kit to check the water. pH is about 6.6-6.8 (slightly acidic) Ammonia 0, Nitrite 0 and Nitrate 0. When the fish got sick I changed over half of the water in the tank and added aquarium salt (which has worked in the past.
In the ten gallon hospital tank, I changed 90% of the water every other day before I added any new doses of medicine.

Any help would be greatly appreciated, thanks in advance.

JN


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## NaomiM (Sep 22, 2012)

Sorry I'm not sure how much help I can be, but didn't want to read and run. Only thing I can think of is that some pathogens may have been introduced with the new fish, that they may have had a level of immunity to, but the wcmm's didn't. Did you put in any of the water from the bag when you introduced the new fish? (I've been caught out that way myself - I lost 5 out of 6 guppies and a platy due to suspected columnaris due to adding pet shop water along with the fish. Never again.)


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## Jodienathan212 (Jun 9, 2014)

Thank you for your feedback 
I may have gotten a tiny bit of pet shop water in my tank, though I was careful. My question now is how do I disinfection the 36 gallon exactly?


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## Phoenix24 (Apr 6, 2013)

Your post was a little confusing to read so I hope you don't mind if I ask a couple of questions.

Did you medicate the main tank with the rosys in?
Did you quarantine the new fish? This is generally recommended especially if you have a spare tank that is running.

Like Naomi the one time I allowed pet shop water in to my tank was the time I lost quite a few fish (white clouds I think!). It may be due to pathogens in the water, or it could have been a temporary ammonia spike due to the addition of new fish and/or the ammonia that builds up in the bag the fish come in. 

Whatever happened, your only real course of action is to (if you haven't already) medicate the main tank for whatever it was you suspected was wrong (I am not familiar with the meds you have used and you didn't mention what they treat), then use carbon in the filter to remove the meds, perform a 50% water change, and then bite the bullet and reintroduce the WCCMs back in. It's quite simple to do - if the two tanks are the same temperature and pH, then just net the fish and put them back in. If there is any difference then bag the white clouds and float them, adding water to the bag every 10 mins for 40 mins, then net them out the bag and into the tank.

I'm afraid that if there is something the rosys are carrying that WCCMs are not immune to then there is little you can do -you might well lose them anyway. Sometimes adding a general tonic to the water when introducing new fish can reduce background nasties, and obviously ensuring that water chemistry is tip top, the new fish are healthy, and that pet shop water doesn't get into the tank, and if you can quarantining new fish for a week or two before putting them in - these are the only things you can do as a precaution. 

Another question: what temperature is the tank? White clouds are temperate fish - they prefer water between 15 and 22 degrees, and should not be kept in a tropical tank. I don't know what a rosy red minnow is - can you provide a latin name? And what do you mean by feeder fish?

ETA: if the white clouds were jumping out the tank, that's generally a sign that either there is something wrong with the water (ammonia spike, for example) or that the rosys were attacking them (sometimes this happens at night).


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## Phoenix24 (Apr 6, 2013)

I forgot to say, don't go about disinfection of the tank just yet. If the rosys are carrying something it will be in them and no amount of disinfection will change that, and you may end up losing more fish because of the loss of bacteria in the filter and having to re-cycle the tank (you would have to put all fish into the hospital tank and again if the rosys are carrying something... you get the idea). You can buy fish tank disinfectors, but really the only sure fire way of a major clean is bleaching everything (this includes the filter) which is a major job - so don't do it, its a last resort.


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## Jodienathan212 (Jun 9, 2014)

Thank you so much for taking the time to answer my post, Phoenix.

To answer your questions:
I have not medicated the main tank with the rosys; nor did I quarantine the new fish being that they looked perfectly healthy.

Kanamycin and Furan 2 are broad spectrum antibiotics which I have read in multiple places may be used together to treat columnaris (I thought maybe that's what my wcmm's had).

The tank's temperature has been around 23-25 degrees celsius.

I have only found one rosy who managed to jump out of the tank.

Rosy reds are also known as Pimephales promelas (http://www.fishlore.com/aquariummagazine/apr09/rosy-red-minnow.htm)

I understand that I am going to need to medicate the rosy reds before I am able to keep them with the wcmm's again and I am in the process of doing so in a separate, smaller tank.

My question now is more about the tank than the fish; I have a 36 gallon tank with plants and about 5 gallons of water; I drained most of the water out. Before I re-introduce my fish back into the 36 gallon tank, what needs to be done to the tank to insure that whatever was in it, that may have caused my fish to get ill, is no longer present? Has anyone had success in just treating the tank/substrate/plants with the same medicine that was used to treat the fish? Another words, can I medicate a near empty tank (no fish present), and what is the best way to go about doing so (the same way I would medicate it if it had fish?) or do I need to disinfect the tank and re cycle it, and can this method be done without changing the substrate?

Any help would be greatly appreciated, thank you!


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## Phoenix24 (Apr 6, 2013)

Well firstly your tank is too warm for either species. Please turn off the heater completely and allow the tank to return to room temperature.

I suppose it depends on how much effort and time you are willing to put in as to the best way to deal with this. And the cost, too.

Are those rosy minnows an expensive fish? And how do the white clouds compare? Over here in the UK white clouds are not expensive, but i'm not sure we have those rosy minnows. The point being, if the white clouds are worth a lot to you, then you are going to have to put a fair bit of effort and time into protecting them - but if they are not then its a case of doing what you can and hoping for the best.

One solution - if you don't want to lose any more white clouds - is to fully disinfect the main tank by bleaching everything, and then performing a full fishless cycle (which could take six weeks) before re-introducing the fish back to it once they have been medicated.

The other extreme is to reintroduce the fish once the course of medication is run, and hope for the best.

With no fish in your main tank you are going to suffer bacterial die-back in the filter anyway, so you are going to have to do some sort of cycle before re-adding any fish anyway.

Even if you bleach everything and treat the rosys for everything you can think of, it might be an infection you cannot identify (or cure), it might be something the rosys carry naturally (and you may or may not rid them of it), or it may be that the white clouds are susceptible to whatever it is, or else are poor stock and get sick again regardless.

It's a tough decision, but whatever you do you are going to have to take the risk of mixing the two fish species again.

And lastly, the problems may simply have been a water chemistry issue - a spike when new fish were added, for example. And i've found that white clouds don't mix well with more competitive fish, too.


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