Brackish Water Aquariums: A Beginner’s Introduction

Brackish water aquariums recreate the mixed salinity of estuaries and mangroves, home to a distinctive group of species not suited to either pure freshwater or full marine setups.

What Makes Water “Brackish”

Brackish water sits between freshwater and full marine salinity, typically measured with the same hydrometer or refractometer used for saltwater tanks, just calibrated to a lower target range.

Popular Brackish Species

Certain gobies, mono fish, scats, and archerfish (known for spitting water to knock down insect prey) are among the more commonly kept brackish species.

Equipment Considerations

A reliable salinity-measuring tool is essential, along with the understanding that some brackish species require increasing salinity as they mature, sometimes eventually needing full marine conditions.

Research Before You Buy

Many brackish species are sold as freshwater fish by mistake, so confirm long-term salinity needs before purchase to avoid future health problems as the fish matures. Browse our freshwater goby selection to explore some brackish-tolerant options.