all these fish are brackish water fish right?

Question

balloon ( or any kind ) molly, guppy, platy and swordtails? I have 40 inches of fish in a 40 gallon. how much salt should I put in for them? thanks peeps

Answer 1

No. Guppies and mollies can be fresh, salt and brackish water fish. I have never seen a swordtail in Salt water.

Answer 2

Mollies are considered brackish fish as they come from the areas of river mouths where saltwater and freshwater mix, in fact many marine aquarists used to use mollies as starter fish (not a common practice anymore).

With mollies they can can kept up to 1.025 specific gravity and all the livebearers do best with a small amount of salt (1 tablespoon per 5 gallons).

Since most livebearers come from areas of high mineral content, they are sensitive to low electrolytes, low calcium and other parameters thet can can be checked via GH, KH and Redox tests.
A GH and KH of 160 ppm or higher is best.
For more information about this and osmotic function that electrolytes provide, I recommend reading these two articles:
http://www.americanaquariumproducts.com/AquariumKH.html
http://aquarium-answers.blogspot.com/2006/12/how-do-fish-drink.html

Answer 3

Swodtails are not typical brackish fish as Danielle pointed out, however I have seen them kept with a considerable amount of salt in the water before to no apparent ill effects. I guess it would really depend on just how salty you plan on keeping the tank and "brackish" covers everything from no salt up to just short of marine.

MM

Answer 4

Yes, In some ways you can assume that they are brackish water fish if you refer to the definition that brackish water contains 0.5-30 ppt Salt (Sodium Chloride) per liter of water.

They prefer 1 teaspoon Salt (approx. 5 grams) per 10 liter or 1/3 teaspoon per gallon, even they can also live and breed in freshwater (salinity less than 0.5 ppt)

For your 40 gallon that would be 13 - 14 teaspoon of salt.

Hope it helps!