Dear brothers and sisters in Christ, my family and those whom God loves:
Fish and aquatic plants live in three general water systems or environments. They are:
🐟 Brackish water, and
🐟 Marine or Saltwater
Freshwater contains less than 0.05% salt, or less than 1% salt by some definitions. This is the kind of water generally found in most lakes and rivers. Freshwater fishkeeping is by far the most popular branch of the hobby and has the greatest number of fish and plants available for sale. One could further divide this category into tropical (fish requiring water to be heated) and temperate (fish that can exist in water at room temperature).
Brackish water contains less than 3% salt. Here is a list of brackish bodies of water. Brackish water aquaria must maintain a salinity between that of freshwater and seawater. There are far fewer species of fish and plants for this kind of aquarium, but there are some common species like mollies that are often sold as freshwater fish that would do better with some salinity.
Saltwater contains more than 3% salt and makes up 96.5% of the world’s water. Most of this water is temperate, ranging from 10-20 degrees Celsius (50 to 68 degrees Fahrenheit) and those who would set up a coldwater aquarium would require a “chiller.” Coldwater species are less than available than tropical marine species even though tropical ocean water is minuscule (0.01%) in comparison to temperate water. Marine aquaria have far more demanding needs and requirements to maintain, and as a result, this system tends to require more experience.
Water is the environment in which fish and aquatic plants live just as the air is our environment as human beings. Maintaining the quality of water will define how well everything lives within your aquarium. Understanding water quality and the factors that impact it is an essential piece of knowledge for those involved in this hobby. If you’re not involved in fishkeeping yet, it may be best to begin with temperate or tropical freshwater fish to develop your knowledge and skills.
God has made us stewards of his creation whether that be our own environment or the environment we keep these small creatures in. God bless you in your stewardship.
Grace be with you,