How to Make and Use Green Water | The All-Purpose Water for Medaka Fish Keeping
Learn how to make and manage green water for medaka fish keeping. We introduce the benefits and precautions.
Key Takeaways
Learn how to make and manage green water for medaka fish keeping. We introduce the benefits and precautions.
Green water (also called blue water) is aquarium water with a rich green color created by abundant plant plankton reproduction. Among medaka fish enthusiasts, it has long been called "all-purpose water" and is used in a wide range of situations, from raising fry to enhancing the color of adult fish. One of its appeals is that it can be easily made at home with sunlight and a little ingenuity, without relying on commercial artificial feed or additives. In this article, we explain green water's benefits and drawbacks, how to make it, and concentration management in an easy-to-understand way for beginners.
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Why Green Water is Ideal for Medaka Fish Keeping
What makes green water superior is not just that it's "green water," but that living microorganisms called plant plankton constantly exist in the water.
Functions as Natural Food
Plant plankton (such as chlorella and euglena) make ideal food for medaka. In particular, fry have extremely small mouths, and sometimes cannot even eat commercially available powdered feed. With green water, plant plankton is always drifting in the water, so fry can feed gradually at their own pace. This is the main reason that dramatically increases fry survival rates.
Contributes to Water Quality Stabilization
Plant plankton absorb ammonia and nitrite as nutrients through photosynthesis. By having plant plankton break down and absorb harmful substances produced from medaka waste, water quality remains stable over extended periods. However, as described later, if the concentration is too high, it can have the opposite effect, so proper management is necessary.
Enhances Vibrant Body Coloration
Plant plankton contains a natural pigment called carotenoid. When medaka consume this, pigments accumulate in the skin and scales, resulting in more vivid body coloration. This is why breeders raising color-focused varieties like Yougui and Orochi prefer green water.
Moderates Rapid Temperature Increases
In outdoor aquaculture, rapid water temperature increases due to direct summer sunlight can be a problem, but green water has low transparency, making it difficult for light to penetrate deep into the water. This creates a gradual shading effect that helps prevent sudden temperature fluctuations.