Not Sure I Can Have These

[Royster]

I saw a tank full of black mollies in a shop a few weeks ago and thought I'd like them for my tank but the more I read up on them the less it looks like I can have them.

I ve read they aren't good for community tanks, which I'm hoping to make mine into, they grow up to be pretty big, which my not be good as I have only a 60l tank and finally they need salt.... So at the minute I have 6 harlequins hoping to move up to 10 so I guess salt isn't good for them.

So could I get 3 or will they not be good in my community tank, will they out grow it and is the water wrong for them anyway. ?

Cheers for the help guys
Rhory

 

[Min8040]

I`ve got 3 mollies in my fresh water tank and are doing fine. One of the females had her fry 4 days ago.
As for putting them in a community tank I don`t know. I`ve got mine in a tank with guppies only.

 

[Tokis-Phoenix]

Hmm A 60 litre tank is a bit on the small side for mollies. Possible, but you might get problems with them. The salt won't benefit the harlequins either, so if you really want black mollies i would advise just getting a bigger new tank for them .

 

[OldMan47]

A 60 litre, I think of it as a 15 gallon, tank is fairly small for mature mollies. All black mollies are an aquarium strain and their ultimate size depends a lot on how they were developed. In all cases, aquarium molly strains do best if they are in water that has a fairly high mineral content and a higher pH of over 7.5. I keep both harlequins and mollies in the same tank but it is not ideal for either one. My water at about 325 ppm of total dissolved solids, TDS, is a bit much for the harleys but is near the minimum for the mollies. My pH from the tap runs about 7.8 which is again a bit high for the rasboras but just fine for the mollies. The end result is that the rasboras in my tank are fairly short lived at only about 3 or 4 years while mollies do not get as much TDS as would best suit them so they also only live 3 or 4 years. If I could optimize the water in that tank for either species, they might well thrive for another year or so. Unlike things like endlers, mollies are not short lived fish. Where 15 months might be a full life for an endler, it is very short for a healthy molly.
If you want the best for both fish, it will take not only separate tanks but manipulating the water in both tanks to optimize the conditions in each tank for its occupants. As a livebearer breeder that simply maintains other fish for decorative purposes, I rarely ever manipulate my hard, high pH, high TDS water in my tanks. I do keep one tank for cories that is a mix of RO water and tap water. When it comes to a water change, that tank turns out to be a PITA but it is a choice I have made, to expand my breeding experiences. Unless you are looking for a challenge, learn what your local water parameters are and choose to keep fish that will thrive in that water.
Your local water authority has lots of information about your tap water and should be willing to give you any information you might want such as typical pH, typical hardness in terms of GH or ppm. Those two simple parameters will define quite well what fish will do best in your water.