Brackish Water Fish Information

When freshwater and saltwater combine, the result is brackish water. The fish and invertebrates that live in brackish water make up a diverse group of creatures, which best thrive in brackish environments. Neither a freshwater or marine environment will provide brackish fish with the right water chemistry, but some freshwater and marine species can thrive in a brackish environment as well.

  1. Geography

    • Brackish environments exist when the ocean's water meets with rivers flowing outward. Examples of brackish environments include estuaries, salt marshes and mangrove swamps. These brackish environments have a water chemistry that is both freshwater and saltwater, and so these environments are not always perfectly suitable for marine fish or freshwater fish. It is important to choose fish species carefully when populating a brackish aquarium or tank.

    Types

    • There is a diverse collection of fish and invertebrate species that thrives in a brackish environment. Examples of brackish water fish include scats, mono sebae, Columbian shark catfish, Ceylon pufferfish, glassfish, Siamese tiger fish, bumble bee gobies and celebes rainbow fish. Fiddler crabs, anableps, mudskippers, archer fish and target fish are other examples of brackish fish and invertebrates. Another notable brackish species is the cichlid, of which there are more than 1300 species identified, according to Caroline Tanaka, DVM.

    Size

    • Because there is such a diverse collection of brackish fish, there are no specific size requirements when it comes to housing them on a general basis. The size of environment that you need to create will depend heavily on the type of brackish environment that you want to create. Although you can create a brackish environment that is 5.5 gallons or 10 gallons, most brackish species thrive in a larger environment, such as an aquarium of 125 gallons or more.

    Brackish Aquarium Environments

    • To create a brackish aquarium, you should aim to recreate a specific type of brackish environment, such as an estuary, a brackish river or a mangrove swamp. Each of these environments is ideal for different species and has specific requirements that you will need to consider. Estuaries are slow to moderate flowing environments ideal for monos, Columbian shark catfish, cichlids and scats. The types of species you should introduce will vary depending on the tank size. Bumble bee gobies are well suited for any sized brackish aquarium, while some species like pufferfish and target fish are suitable for large tanks.

    Misconceptions

    • There is a common misconception that because brackish water is a mix of marine water and fresh water, that any marine or fresh water species can survive comfortably in a brackish environment. While there are some situations where a freshwater fish or a marine fish can survive or thrive in a brackish environment, this is an exception to the rule; most fish are accustomed to one or the other. It is important to choose fish carefully when populating a brackish water aquarium.