HOW MUCH SALT DO YOU HAVE TO ADD TO A 40 GAL TANK TO MAKE IT A BRACKISH AQUARIUM?

most eels sold as freshwater are actually brackish,

but most eels sold as snowflake eels are actually marine/full salt water.

As juveniles they live in fresh to brackish environments briefly, before moving to salt water.

You need to check into exactly what eel you have, and then look for a reliable care sheet for the specific eel. As you know there's some bogus info out there as well, so look for more than one source.

Note: if you bought it at 7seas, I'd expect someone there should be able to tell you what it is. If you bought it at petco, well, nobody there will know anything usually.

EDIT: forgot to answer the question,

1. don't add all the salt at once, add it over a week period

2. the total will be about 4 tablespoons per 10 gallon . Use freshwater aquarium salt, or marine salt mix, not table salt.

So add 1 tablespoon per 10 gallon, and do it four times.

3. eventually you will need a hydrometer and want a reading of about 1.010 I think for the juvenile eel.

If there is some other problem with your tank then make sure you handle that as well. Just changing the salt won't solve other problems.

Just FYI, a 40 gallon is WAYYYYYYYYYY to small for an eel. I don't care what the pet store told you when you bought it, that sucker will get well over 5 feet. If they told you other wise BS. Those eels get 5+ feet as I looked into getting one for my 350 gallon. I have never heard of adding salt to make a tank brackish. Add too much salt and you can kill it,I highly recommend NOT putting salt in af reshwater tank. Regardless of what the experts say. Salt doesn't do a damn thing.

A picture of your Snowflake Eel would be greatly appreciated.

I am under the impression that it may be a marine specimen. I have done some research and there are different Eels that are labled Snowflakes, some can be FW, other need BW and later SW.