they don't need it ,but they prefer it.
Mollies are a type of freshwater fish and do not require salt in their water. In fact, adding salt to their tank can be harmful to them. It is best to keep mollies in freshwater with good quality water parameters.
Silver Mollies need fresh water
No they do not "need" salt in their water. Mollies (Poecilia sp.) originally came from brackish (Estuarine) waters and provided it is done very slowly they can eventully live in a marine environment, but they have been kept and bred in fresh water for so long now that salt is not a neccessity as it once was 60 years ago.
none because mollies need 5gallons and up
6 foot
I don't recommend it. Mollies can get larger than a Betta (Siamese Fighting Fish) and be far more bullish than a Betta. A Betta could easily get beaten up by Mollies! Mollies need a minimum of 20 US gallons anyway.
Yes, Mollies have scales.
Mollies are active swimmers that require adequate space, filtration, and water quality to thrive. A fish bowl is generally not suitable for mollies as it does not provide enough space or proper filtration to support their needs. It is recommended to house mollies in a larger tank with appropriate conditions.
Mollies need more space than 20 litres. With the number of babies that have been born, you now need at least 115 litres for your fish.
Might be time to get a tank divider to separate them. Although, typically, mollies don't eat tetras usually unless they are fry.
They're designed for salt water, not fresh water! Just the way they are made. You can get aquarium salt from your local pet store, but don't put any in there if you have other freshwater fish that don't need it. Or get a tropical freshwater fish like mollies instead!
Gold Barb (Puntius semifasciolatus) are a fairly small, peacefull fish (about 3" max) with a fairly small mouth. Adult Guppies and Mollies would be far too big for the Barb to eat. They will of course eat youngsters (fry) though, as will just about every other species of fish.