Adding fish to qt during treatment

[Liron Mishal]

I have 3 fish in qt which should end in a week.
All 3 looks great. I intend to finish the qt before adding a new batch of fish.
I'm curious: many say that if you introduce a new fish to an ongoing qt, the countdown restarts, but why?
The latest qt procedure by @Humblefish says to move the fish into a sterile qt after 14 days of copper treatment.
The logic as i understand it is that all ich should have fallen off the fish and the copper should prevent reinfection.
Following this logic, wouldn't copper prevent the first batch of fish from reinfection by the new fish?

 

[Thomashtom]

You dont know what the new fish have?

 

[Liron Mishal]

If its ich or velvet, they are covered by the copper
In any case, a prazipro treatment is followed at a sterile qt

 

[SteveC]

There is no copper in the sterile tank! Your new fish could re-infect the QT ‘d fish.

 

[ap7x]

You’re right - the new fish wouldn’t reset the old fish timeline in copper for ich/velvet to transfer to sterile tank since no new theront should be able to infect the old fish.

But the bigger issue is the new fish being dropped into that high level of copper immediately (and if you are bringing copper down for new fish, then timeline on original fish would reset since it’s sub-therapeutic).

 

[Liron Mishal]

@ap7x Ok, so what if we had an acclimation tank to slowly raise copper to the qt level?
That would eliminate the copper shock and allow us to use the same qt in batches.
I like the idea of keeping a 2ppm qt and a small tank for acclimation.

The idea is that sometimes you stumble across a great deal but your qt is already in progress..
So either pass or setup another qt.. not ideal

 

[SteveC]

Sorry liron,
I misunderstood your question initially. Could there be any disease, bacterial infection, or other beside ich or velvet that could infect in the QT?

 

[Liron Mishal]

That's always an unknown and a valid point.
I really don't know if bacterial infections can move from fish to fish but I guess its very much possible.
I wonder what the disease experts would have to say about it..

 

[SteveC]

There also could be a situation arise where you may need to reduce the therapeutic copper level to treat another illness of the new fish. That could complicate things a bit.

 

[EmdeReef]

I have 3 fish in qt which should end in a week.
All 3 looks great. I intend to finish the qt before adding a new batch of fish.
I'm curious: many say that if you introduce a new fish to an ongoing qt, the countdown restarts, but why?
The latest qt procedure by @Humblefish says to move the fish into a sterile qt after 14 days of copper treatment.
The logic as i understand it is that all ich should have fallen off the fish and the copper should prevent reinfection.
Following this logic, wouldn't copper prevent the first batch of fish from reinfection by the new fish?

Copper only affects theronts. I can’t recall off the top of my head but think that the mortality+reduced motility amounted to 99%.

Fish can still technically get infected while in therapeutic copper for as long as 1 theront finds a host before copper kills it. It’s rare but it can happen. The rate of infection would likely pass as subclinical without tissue analysis. The “infectious load” reduces with every cycle copper breaks. If you introduce a new sick fish you increase the infectious load and thus add time to the clock.

 

[AcroNem]

It is policy in every official quarantine protocol that no new fish be introduced to a batch that is already in a quarantine system, or the entire treatment process starts over.

If your new fish has not been 100% prophylactically treated before you introduce it to your newly clean fish after you pull them from copper, or even if they're in copper, they can be reinfected. So the timeline starts over.

 

[Big G]

I really don't know if bacterial infections can move from fish to fish but I guess its very much possible.

Yes, bacterial infections can move from fish to fish. Always a good idea to isolate a fish with a bacterial infection in a separate QT.

 

[ap7x]

@ap7x Ok, so what if we had an acclimation tank to slowly raise copper to the qt level?
That would eliminate the copper shock and allow us to use the same qt in batches.
I like the idea of keeping a 2ppm qt and a small tank for acclimation.

The idea is that sometimes you stumble across a great deal but your qt is already in progress..
So either pass or setup another qt.. not ideal

So technically, yes, if you acclimate new fish to therapeutic copper levels, then add them to a copper QT with fish in it, the addition of the new fish shouldn't affect the timeline of the original fish for ich/velvet. This is assuming that copper at therapeutic always kills/damages free swimming ich/velvet on the first go (but obviously this same assumption applies to 10-14 days transfer to sterile as well since... if even one free swimmer has a chance to attach and continue their life cycle successfully in therapeutic copper (as proposed by some members above), then the 10-14 days wouldn't be enough time too. Guess that's what the sterile tank observation is also for, but that sucks since if just 1 theront makes it, how long until symptoms show from 1 single ich theront reproducing? Maybe too late and fish are already in DT? That's a scary thought).

I know you had a very specific question regarding copper and ich/velvet, so I answered it specifically. But the others bring up good points. It's not just ich/velvet that fish can bring in. So then you open yourself up to having a juggling act of trying to decide which fish has what, or let's say you have 5 fish in the copper QT that seem healthy and then #6 brings in brook... now you have 6 fish you have to treat for brook/hope they survive long enough rather than 1. And everyone can probably chime in with random things that could arise (or never arise and everything goes as planned!) Guess you have to decide if that special deal is worth it to you or not. Just food for thought.

 

[Liron Mishal]

Thanks for the elaborated answers.
as my qt ends next Friday, after observing and treating with copper and prazipro, without any symptoms,
No way i am going to risk it, was just curious.