Your Medaka Just Arrived

Before you open anything

Open the shipping box indoors, out of direct sun, and check the bag with the fish still sealed inside. If something has gone wrong in transit, photograph the unopened bag right away and contact me the same day. That is all my live arrival guarantee asks of you, and it lets me make it right without any back and forth.

Assuming everyone is swimming, and they almost always are, take a breath. The water in that bag looks dirty and the fish look washed out. Both are normal after two days in transit. Colour comes back over the first week.

Step 1: float the bag, 15 to 20 minutes

Set the sealed bag on the surface of the water it is moving into and leave it alone for 15 to 20 minutes. This does one job: it matches the bag's temperature to the tub's, slowly. Temperature shock is the most common acclimation mistake, and floating is the entire cure. If your container is outdoors in strong sun, shade the bag with a towel while it floats, since a dark bag in sunlight heats fast.

Step 2: mix the water, gradually

Open the bag, roll the top down to make a collar so it floats open, and add roughly half a cup of your water to the bag. Wait five minutes. Do it twice more, five minutes apart. This lets the fish adjust to your water's chemistry at a walking pace rather than all at once.

Medaka are hardy and forgiving fish, which is exactly why this gentle version of acclimation is enough. You do not need drip lines or airline tubing for medaka. Slow and simple does it.

Step 3: net them out, leave the water

Lift each fish out with a soft net, or gently pour the bag through the net over a bucket, and release the fish into their new home. Welcome home! The shipping water goes down the drain, not into your tub. Two-day-old bag water is the one part of the package you do not want to keep.

If there are snails in your box

Snails travel differently than the fish: they ship nestled in a damp paper towel rather than a bag of water, since they are happiest moist but not submerged in transit. That means there is no bag to float. Unwrap them gently and lower them right side up to the bottom of their new tank, tub, or pond. They will likely stay sealed behind the trapdoor for a few hours while they settle, sometimes as long as a day, and that is completely normal. They open up and get to work when they are ready. If your water is much colder or warmer than the room they arrived in, rest them in a cup of tank water for ten minutes first, though with trapdoors it is rarely necessary. They are the tough ones in the box.

The first 48 hours: what is normal

Hiding is normal. New fish bolt for cover and stay there, sometimes for a day or two. Plant cover actually shortens this, because a fish that feels hidden calms down faster.

Pale colour is normal. Stress mutes their colour. It returns as they settle.

Not eating is normal, and do not feed them on day one. Their systems are slowed from transit and uneaten food only fouls the water. Offer a small pinch on day two, and take it as a good sign when they rise for it.

Jumping risk is at its lifetime peak. The first nights in a new container are when medaka are most likely to jump. Keep a few inches between the waterline and the rim, and read my guide on jumping if your setup is tight.

Where they should be going

The ideal receiving container has been set up and running for a while: settled water, some plant cover, and no other new arrivals that same week. If you are still cycling a brand-new setup, my care guide covers what ready looks like. And if your fish have not arrived yet, this is the moment to get the container ahead of them, since there is a box at checkout to delay your shipment until your setup is ready.