Using Mollies to confirm Fallow Ich Eradication

[Sean W.]

Hey Guys,

I am at the tail end of my 45 day fallow period @ 86F+.

I don't want to have to do all this again if the fallow was not successful. I have been mixing up the sand, and running my wave makers at 100%.

I wanted to ask about the workflow of using a Molly to confirm ich eradiation from the display tank.

It's my understanding that a Molly can be a canary in the mine of sorts.

My question is, do I need to QT a Molly before it goes in the display tank, or would anything a freshwater Molly could bring over die in saltwater anyway?

It's my understanding that a freshwater molly has no natural immunity to any marine diseases and would show signs of infection/infestation very quickly if there is any marine ich left in the tank.

Thanks for any help!

 

[Jmcg89]

It was my understanding when I tried this that there weren't any diseases that would cross over so no qt was needed. I took a good while to raise salinity i wanna say a day floating in the sump in a container and all four survived.
After a day in the acclimation box in the display I let them out and my hippo tang went after them like an orca whale on a pack of seals.
Needless to say I did not finish the experiment....

 

[Jmcg89]

This was 8 months or so ago and I haven't seen any signs of any diseases on any of my fish.

 

[Sean W.]

You had a hippo tang in the tank? Were you doing fallow period to eradicate ich?

 

[Enderg60]

If you want to make sure, and you want an ich canary....get a powder blue tang.

 

[Sean W.]

If you want to make sure, and you want an ich canary....get a powder blue tang.

a powder blue tang can bring infections into the tank... a QT would be required and if it gets infested after it goes into the DT, it would be impossible to know if it got sick from a failed QT or the fallow period failed.

I'm trying to isolate the problem down to if the fallow period was successful or not.

 

[Mr. Mojo Rising]

the mollie might survive, or it die right away, or after a few days from not being able to acclimate to saltwater. Then you will have a dead fish and no idea why it died, it could be disease, or it could be failure to acclimate. Sorry but i dont think its a great idea.

 

[Jmcg89]

You had a hippo tang in the tank? Were you doing fallow period to eradicate ich?

I had previously done a 72 day fallow period and was just wanting to test the display after all the fish had been added again.

 

[Sean W.]

the mollie might survive, or it die right away, or after a few days from not being able to acclimate to saltwater. Then you will have a dead fish and no idea why it died, it could be disease, or it could be failure to acclimate. Sorry but i dont think its a great idea.

It's best to use ~4 or so mollies for this reason

 

[Jay Hemdal Verified Community Expert]

Hey Guys,

I am at the tail end of my 45 day fallow period @ 86F+.

I don't want to have to do all this again if the fallow was not successful. I have been mixing up the sand, and running my wave makers at 100%.

I wanted to ask about the workflow of using a Molly to confirm ich eradiation from the display tank.

It's my understanding that a Molly can be a canary in the mine of sorts.

My question is, do I need to QT a Molly before it goes in the display tank, or would anything a freshwater Molly could bring over die in saltwater anyway?

It's my understanding that a freshwater molly has no natural immunity to any marine diseases and would show signs of infection/infestation very quickly if there is any marine ich left in the tank.

Thanks for any help!

This topic comes up from time to time. I wrote up a synopsis of the technique here:

Using black mollies to screen an aquarium for Cryptocaryon

In recent years, a procedure has been promoted that uses marine-adapted freshwater mollies to screen for active Cryptocaryon infections in marine aquariums. The thought is that freshwater black mollies that are naïve to marine ectoparasites, will soon develop infections if that disease is present in a marine aquarium.

With mollies being stark black, white parasites will show up in sharp contrast, making their identification much easier. Mollies have also been suggested to be housed alongside sensitive fish (that cannot be easily medicated) to serve as a “canary in the coal mine” for active disease.

The basic process is to acquire a small group of freshwater black mollies and gradually acclimate them to seawater over a period of 5 to 7 days. They then are added to the previously fallow aquarium, or added to the quarantine tank, and then observed for at least two weeks to see if they develop ectoparasites. If they do, then a treatment needs to be instituted, or the fallow period extended.

As with many aquarium ideas, over-extrapolation can reduce the effectiveness of the original idea. The process is really only suited to screen for Cryptocaryon. Brooklynella may not even infect mollies. Uronema and Amyloodinium can survive salinities as low as 3 ppt so may already be present in “freshwater” mollies that have been raised in brackish fish ponds. Marine and freshwater fish have basically the same internal salinity. Therefore, untreatable internal diseases, such as viruses and Myxozoans could possibly be brought into an aquarium with the mollies.

There is a risk for introducing euryhaline trematodes into an aquarium along with black mollies. Fish farmers, wholesalers and retail dealers all understand that mollies benefit from being housed in brackish water, and so they usually add salt to systems housing mollies in order to reduce mortality under crowded conditions. Euryhaline trematodes take advantage of this, the trouble is that some of these can survive marine conditions and then hyposalinity is ineffective as a treatment for them.

Finally, there is no scientific evidence to indicate this method is actually effective, it is based on a theory, but it needs to be better tested. If properly applied, this process may have some benefit in screening for Cryptocaryon, but falls short for other diseases.


Jay

 

[Sean W.]

This topic comes up from time to time. I wrote up a synopsis of the technique here:

Using black mollies to screen an aquarium for Cryptocaryon

In recent years, a procedure has been promoted that uses marine-adapted freshwater mollies to screen for active Cryptocaryon infections in marine aquariums. The thought is that freshwater black mollies that are naïve to marine ectoparasites, will soon develop infections if that disease is present in a marine aquarium.

With mollies being stark black, white parasites will show up in sharp contrast, making their identification much easier. Mollies have also been suggested to be housed alongside sensitive fish (that cannot be easily medicated) to serve as a “canary in the coal mine” for active disease.

The basic process is to acquire a small group of freshwater black mollies and gradually acclimate them to seawater over a period of 5 to 7 days. They then are added to the previously fallow aquarium, or added to the quarantine tank, and then observed for at least two weeks to see if they develop ectoparasites. If they do, then a treatment needs to be instituted, or the fallow period extended.

As with many aquarium ideas, over-extrapolation can reduce the effectiveness of the original idea. The process is really only suited to screen for Cryptocaryon. Brooklynella may not even infect mollies. Uronema and Amyloodinium can survive salinities as low as 3 ppt so may already be present in “freshwater” mollies that have been raised in brackish fish ponds. Marine and freshwater fish have basically the same internal salinity. Therefore, untreatable internal diseases, such as viruses and Myxozoans could possibly be brought into an aquarium with the mollies.

There is a risk for introducing euryhaline trematodes into an aquarium along with black mollies. Fish farmers, wholesalers and retail dealers all understand that mollies benefit from being housed in brackish water, and so they usually add salt to systems housing mollies in order to reduce mortality under crowded conditions. Euryhaline trematodes take advantage of this, the trouble is that some of these can survive marine conditions and then hyposalinity is ineffective as a treatment for them.

Finally, there is no scientific evidence to indicate this method is actually effective, it is based on a theory, but it needs to be better tested. If properly applied, this process may have some benefit in screening for Cryptocaryon, but falls short for other diseases.


Jay

What would you say is the best way to confirm a fallow period was successful or not? Is there a way other than crossing your fingers?

As it turns out, I will be traveling until the middle of September so won't be able to begin QTing fish until I get back. So at the very EARLIEST, fish will go in after maintaining an 87°f+ fallow period for 8 weeks.

 

[Jay Hemdal Verified Community Expert]

What would you say is the best way to confirm a fallow period was successful or not? Is there a way other than crossing your fingers?

As it turns out, I will be traveling until the middle of September so won't be able to begin QTing fish until I get back. So at the very EARLIEST, fish will go in after maintaining an 87°f+ fallow period for 8 weeks.

87 F. for 8 weeks is plenty long enough for a complete fallow. If ich shows up after that, it came back in on fish or corals....

Jay