Healthcare & Medication

As mentioned in the introduction, one of the best low-technology ways to keep brackish water healthy is to vary the salinity. While these fishes are well adapted to fluctuations, many common external parasites are not. Simply exposing freshwater whitespot to full strength seawater will kill it and all its spores. The reverse is true for marine pathogens: expose them to freshwater and they will die. The simplest option is to remove the infected fish and dip it into a bucket of fresh- or saltwater as required. If several fishes are infected, then an option for an aquarium with hardy brackish water species like scats or monos, it is simple enough to change the salinity of the aquarium for a few days. Make the change gradually, over a few hours, and keep an eye on nitrite levels. The filter bacteria should be okay, but as a precaution remove some of the filter media before making the salinity changes. This reserved media can be put back into the filter if something goes wrong, with the salinity returned to its original level of course. Not all brackish water fishes will tolerate big changes in salinity (e.g. rainbowfish, spiny eels); see the lists of species below for details.

Commercially available remedies can be used in brackish water aquaria. In lightly salted water (1.005 or less) freshwater branded chemicals can be used, but in general marine chemicals are better. Never use freshwater remedies if you are keeping invertebrates, since these frequently contain copper which will kill many molluscs and crustaceans.