"Fresh" vs. "Brackish" - Salt when and whys.

[bookseller]

I'm a little confused about Aquarium Salt and "Fresh" vs. "Brackish". I have some Molly's (3 adults and about 12 fry) in a 10 gal tank that were doing fine in "fresh" water. I read a post and also read in a book that molly's are a "brackish" fish and need some salt. I added some two teaspoons as per instructions (added a bit aver a few days for a gradual change) on the Aquarium Salt box. My two cory cats promtly died but my one albino cat is strong and active.

My confusion is this:
- Product information on box seems to indicate that aquarium salt is good for all setups. ("reduces stress", "improves gill function", etc, etc)
- But why would you want to ad salt to "fresh water" fish?
- I read one book that said this amount of salt won't hurt other fish.
- I read one book that said salt was harmful to corys (which I proved out, but why is the albino cat OK?)

Can someone help explain this? I have conflicting information...

 

[Alien Anna]

Mollies naturally come from estuaries where sea and fresh water may mix. However, the concentration of salt they have in the wild varies considerably, so an argument could be made for putting them with salt, or without. Some people even keep mollies in sea water tanks!

The advantage of salt is that it kills many parasites (such as ich) and many harmful bacteria and fungi can't thrive in it. So it keeps the fish healthy. However, I am highly sceptical of some of the health claims - I think if they said that about human food supplements, they'd get into trouble with the FSA/FDA.

Corys as you confirmed can't really cope with salt, except maybe in small quantities (a quarter of the levels you tried). Neither can plecos, tetras or pencilfish. However, a tiny amount of salt doesn't seem to be here nor there.

If you keep corys and mollies together you need to find a compromise: either a tiny dose of salt, so as not to harm the corys, or fresh water and keep it clean and a suitable temperature to avoid problems with your mollies. However, for more reasons than salt, they aren't terribly compatible fish.

 

[Whisper Odinsky]

dear anna-
my little clown loaches have ich in the tank, there is a little, little pleco- do i take him out, and let him chill in a hospital tank while i add salt to the tank, and if i do that, how long do i wait until that cute little guy can go back in? i would feel heartbroken if i ended up hurting him. also- i have a *rainbow shark* and he has whiskers.. here is a photo- i don't want to hurt him either.- will he be affected by salt?

 

[CFC]

Do not add salt to the tank! Clown loaches too are scaleless and will not tolerate salt well. Treat the ICH by raising the temperature to 30 degrees celsius and using a appropriate medication, prefferably one that says it is suitable for scaleless fish, if not use a normal medication at half dose. Continue with the treatment until 5 days have passed since the last sign of white spots on the fish.