Do tropical fish need hard or soft water to survive?

The water hardness preference of tropical fish varies depending on the species. Some fish are adapted to living in hard water, while others prefer soft water. In general, fish from regions with acidic, tannin-stained waters, such as the Amazon River Basin, prefer soft water, while fish from regions with alkaline, mineral-rich waters, such as Lake Tanganyika, prefer hard water.

It's important to provide tropical fish with water that is within their preferred hardness range. Keeping them in water that is too hard or too soft can cause health problems. If you're not sure what the water hardness preference of your tropical fish is, you can ask your local fish store or do some research online.

Here are some general guidelines for tropical fish water hardness:

* Soft water: 0-8 dH

* Moderately hard water: 9-15 dH

* Hard water: 16-30 dH