How We Quarantine New Medaka

As soon as new fish arrive, they go into a completely separate quarantine tank or tub.

We prefer stable, cycled, aged water for quarantine. Newly imported fish have already been through enough change, so we try to make their new environment as stable as possible from the beginning.

The quarantine setup itself is intentionally simple.

We do not use plants, substrate, or unnecessary decorations that make it harder to see the fish.

A plain tank or tub allows us to notice small changes quickly.

If one fish begins isolating itself, clamping its fins, breathing differently, losing weight, or swimming strangely, we want to see it right away.

Even when every fish looks healthy on arrival, we do not skip this step.

Before transferring the fish, we check the temperature and avoid a sudden change between the shipping water and the quarantine system.

For standard shipping bags, we allow the temperature to gradually come closer before transferring the fish.

Breather bags are handled differently because they are designed to exchange gases through the bag material and should not be treated exactly like a standard shipping bag.

Our quarantine systems are generally kept around 75°F when appropriate, although the exact temperature can change depending on the season and the conditions the fish were coming from.

After a long shipment, the goal is to avoid adding another major temperature change on top of the stress they have already experienced.

Once the temperature is reasonably close, we carefully transfer the fish into the quarantine system.

We avoid transferring unnecessary shipping water whenever possible.

We also do not immediately add several medications simply because the fish were imported.

The first 24 hours can tell us a lot.

We give the fish time to settle while watching them closely.

It is normal for newly imported fish to look pale, quiet, or tired at first. They have just completed a long trip and entered a new environment.

What matters is the direction they are going after they settle in.

If something clearly looks wrong, we do not wait several days simply because the original plan was to observe first. When a fish needs attention, we respond.

The first 10 days to 2 weeks are especially important.

Not every problem appears immediately after arrival. This is often when parasites, infections, or weakness related to shipping stress become easier to recognize.

We check the fish every day.

The sooner we notice a pattern, the sooner we can decide what needs to be done.

We start feeding lightly.

One of the first things we want to see is whether the fish show interest in food and are able to eat normally.

Good nutrition is important for recovery, but feeding too heavily too soon can quickly create water quality problems.

During this stage, stable water and careful observation are more important than trying to push growth.

If a fish does not look right, we do not simply wait and hope the problem disappears.

We look at the fish's behavior, visible symptoms, and whether the same problem is appearing in other fish from the group.

When appropriate, microscopic examination can also help determine whether an external parasite may be involved.

A skin scrape, fin sample, or gill sample can sometimes help identify problems such as flukes, Trichodina, Costia or Ichthyobodo, Ich, and other external parasites.

This matters because not every sick fish needs the same medication. The better we understand what we are dealing with, the easier it is to choose an appropriate treatment instead of treating blindly.

A separate quarantine tank does not help much if contaminated equipment is moved from one tank to another.

Nets, bowls, siphons, and other tools can carry problems between groups, which is why equipment sanitation is part of our quarantine process.

For equipment sanitation, products such as potassium permanganate or an aquaculture disinfectant such as Virkon Aquatic may be used according to the product directions.

Equipment disinfectants are part of the biosecurity process. A product used for sanitizing a net is not automatically something that should be added to the water with the fish.

For someone adding new medaka to a personal collection, we think around 30 days of quarantine is an excellent goal whenever possible.

That extra time gives problems that may not be obvious on arrival more time to show themselves before the fish enter an established collection.

Imported fish work a little differently for us.

SNR Medaka USA works together with SNR Medaka Korea. Fish being prepared for export are observed and go through a quarantine and health check process in Korea before they are shipped to the United States.

Once they arrive here, they go through another quarantine and observation period at SNR Medaka USA.

Because part of the process has already taken place before export, the US portion can sometimes be shorter than a full 30 day quarantine.

There is also a practical side to importing. Many of these fish already have customers waiting for them, and we want to get them to their new homes as soon as it is reasonable and safe to do so.

But every fish does not leave quarantine on the same day.

The condition of the fish matters more than the calendar.

If treatment is needed, we treat the fish and continue observing them. If additional screening is needed, we do that as well.

We do not want to clear a fish while there is still a concern about its condition.

Looking good for one or two days is not enough by itself.

Before a fish leaves quarantine, we want to see consistent signs that it has adjusted and recovered.

If something is questionable, the fish stays in quarantine longer.

The calendar does not clear the fish. The condition of the fish does.