New Fish and Acclimation
By Yechiel Kuperman, marine biologist · 49 years keeping fishTold by Madame Molly — the Peacekeeper
“Fresh, salty, in-between — breathe first. That is the advice I give to everyone who arrives in a new body of water. The water in your bag is not the water in this tank. The temperature is different. The bacteria are different. You cannot simply be poured in. No one can simply be poured in. We adjust. We adapt. But we do it slowly.”
The water in a transport bag is not the same as the water in the tank. Even if they are both labelled “freshwater,” the temperature, pH, hardness, and mineral content may all be different. Pouring a fish directly from one to the other is a shock to its entire system.
The right process is slow and patient. Float the bag in the tank for fifteen minutes to equalise temperature. Then, gradually, add small amounts of tank water to the bag over another fifteen to twenty minutes. This gives the fish time to adjust gently. Then — carefully — transfer the fish into the tank. Drip acclimation (letting water drip slowly from the tank into the bag via a small tube) is even gentler and is especially important for delicate species.
⚠️ Never just pour a fish from the bag into the tank. Temperature shock and water shock can harm a fish that arrived completely healthy.
Yechiel's Rule
Slow is kind. Float first, add water gradually, then transfer. The fish will thank you by surviving.
🎮 Practise it in the game
“Take It Slow” is this guide, as a game — drip a fish's new water in gently and learn to read how they feel. Free, no download.
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