Why Do Some Fish Require Aquarium Salt?

Fish are cold-blooded, aquatic, vertebrates of the scientific phylum Chordata. Fish encompass more than 30,000 species and occur naturally in almost every body of water worldwide. For thousands of years, people have consumed fish and have been known to display fish in aquariums in ancient Asia, Egypt and Rome. While aquarium fish generally thrive in environments that are either strictly freshwater or saltwater/marine, many require freshwater habitats with small amounts of added aquarium salt.

  1. Salt Types

    • Aquarium salt, marine salt and table salt have a base of sodium chloride, but are distinctly different substances. Table salt is sodium chloride that usually contains additives including calcium silicate and iodine, and is suitable for human consumption.

      Marine salt is composed of sodium chloride and special mineral blends that are consistent with the sea and ocean fish habitats found in nature. Sometimes marine salt is sold as sea-marine salt or synthetic sea salt.

      Aquarium salt also consists of sodium chloride, but it doesn̵7;t contain substantive additives, except for a small amount of anti-caking agent. So, in creating a healthy environment for fish, using marine salt in aquariums for fish that are indigenous to saltwater habitats is best. Aquarium salt is appropriate for freshwater treatments and as an option in creating brackish water environments. Using regular table salt for fish aquariums in any instance is not recommended.

    Osmoregulation and Aquarium Salt

    • The way that animals regulate the ratio of water and salt within their bodies is done through a process called osmoregulation. The mechanics of osmoregulation varies with the type of organism. For example, osmoregulation is facilitated through kidney function in people verses osmosis in freshwater fish. In times of stress or illness, fish can have problems with osmoregulation and experience various symptoms including osmotic shock. Experts, including Foster and Smith Aquatics and Aquarium Fish Wonders, report that adding aquarium salt will help stabilize this condition and address other issues on a short-term basis such as protection from nitrite poisoning and parasites.

    Brackish Water

    • In nature, brackish water is found at the junction of where fresh and marine waters meet. The end result is a section of water that is a hybrid of the two water types -- being neither fully freshwater nor saltwater. There are many fish that live in brackish water, and in turn, numerous pet owners choose to recreate brackish habitats for species that flourish in those environments. While there are various products on the market used for brackish habitats --- including marine salt -- FishChannel.com states that aquarium salt is also suitable for brackish water aquariums.

    Fish Species

    • While most freshwater fish species can benefit from aquarium salt for medicinal purposes, not all species thrive in brackish water. Examples of larger species that live in brackish water and need a tank size of at least a 36 inches includes scats from the genuses/genera Selenotoca and Scatophagus; monos or fingerfish in the genus Monodactylus; and archerfish of the genus Toxotes. Mid-sized fish needing 24-inch tanks include spotted green pufferfish or Tetraodon fluvialitis; wrestling halfbeaks or Dermogenys pusilla; and orange chromide cichlid or Etropulus maculates. Small brackish water fish that only require 16-inch tanks include limias of the genus Limia; bumblebee gobies of the genus Brachygobius; and the species Heterandria Formosa.