Freshwater fish do best with practically no salt in their water. Brackish water fish can usually live in fresh water or sea water, but do best in water that is a mixture of about 1/7 sea water and 6/7 fresh water.

We recommend keeping brackish water fish in freshwater with about 1 Tablespoon of Aquarium Salt per each 5 gallons of water. Click here for more about Aquarium Salt.

Almost all aquarium fish can tolerate brackish water with one Tablespoon of Aquarium Salt per each five gallons of water. For example, all Livebearers, all Cichlids, all Goldfish and Koi, all Barbs, all Gouramis, and all Danios can tolerate this amount of Aquarium Salt. I have used Aquarium Salt on all the freshwater fish listed on this website.

In this web site I use the generic phrase "marine salts" as a description of the salt in marine sea water. The synthetic sea salts that you mention is a man made combination of nearly the same salts that are found in marine sea water.

For many years we put synthetic sea salts in the water of our Brackish Water Fish rather than Aquarium Salt. We kept detailed records of all the fish we bought and sold, and we regularly printed out summaries of these records, which showed that we should try to improve the way we handled Brackish Water Fish.

I remember my brother, Nevin, suggested that we try switching from synthetic sea salts to Aquarium Salt. His suggestion of this switch surprised me, because I knew that most Brackish Water naturally live in both freshwater and marine water, so it seem to make sense to add synthetic sea salts to their water.

I remember that I asked my brother, why switch to Aquarium Salt? He said he thought the pH might be too high with synthetic sea salts. After adding the synthetic sea salts, the pH of the water in our aquariums increased to well above 8.

We don't talk too much about pH in this web site. We've found that many beginning aquarists are too concerned about pH, and it distracts them from other more important factors. But synthetic sea salts do increase the pH, and a higher pH makes ammonia more toxic to fish. Aquarium Salt does not change the pH of water.

We tried putting Aquarium Salt in the water with our Brackish Water Fish, and they seemed to do much better. We have regularly checked the summaries of our data, since we switched from the synthetic sea salts to Aquarium Salt, and the summaries show that the statistics for our Brackish Water Fish have greatly improved.

So based on our experiences in our aquariums with our fish, we are rather certain that Aquarium Salt works better for us than the synthetic sea salts did. But like all the advice given on this web site, it might not work better for you.

Let me emphasize that you must watch your fish and try to see if they look good and are healthy. Compare the way your fish look to the way the fish look in various stores that sell fish. Go to public aquariums and look at the fish very carefully. Look at the pictures in books and on web sites. Try to learn how to tell the difference between healthy fish and not-so-healthy fish by just looking at them.

When fish are feeling good, they usually hold their fins up high and swim smoothly with very little effort. But when fish are not feeling good, they will often clamp their fins against their bodies, or swim with a shimmy that takes more effort, and sick fish usually don't eat well. Click here to read more about Signs of Stress and Disease.

If your fish look like they have Signs of Stress and Disease, then you must think about what has caused the problem, which will rarely be the pH. Most often it will be poor water quality caused by uneaten food, or old stale water, or changing too much water on one day. Click here to read more about the Essentials of Fish Care.

Finally, let me add a comment. Many brackish water fish spawn in fresh water then migrate to marine water, where they mature. Later they return to spawn in fresh water. Most of the brackish water fish we keep here in our facility are young fish, and perhaps these young brackish water fish prefer freshwater, or freshwater with some Aquarium Salt.

We don't have a lot of experience with adult brackish water fish, and they may prefer water with more salt and perhaps synthetic sea salts instead of Aquarium Salt. So the advice, that you gave in your email shown above, may be better for adult Brackish Water Fish.

You might enjoy reading the story about how Mr. Wesley Way spawned Monodactylus sebae, which is a brackish water fish. Click here to go to that page now and read about Mr. Wey.