I have a 12 gallon tank with 1 Male 2 Female Sailfin Mollies and im wondering if i can add in some fancy guppies? Will the sailfin molly attack the guppy like it did with my other male sailfin molly(which i gave away :P)? If i can add in guppies, how many? And must i add females? Thanks. btw: My sailfin mollies are not fully sized, male is like 6 cm while females are around 4(including the tail)

Tbh, you're already a bit overstocked. 12 gallons is a bit tight for the Sailfin Molly. You should be keeping up with 40% weekly water changes, if get a stronger filter you can change that to 20%. You really don't want to add any more fish to that tiny tank.

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I agree with Pigeonfish, you won't be able to have anything else in the tank since the Mollies are a bigger fish. Plus you will probably have fry, so you'll have to worry about them too. I'd get a 20 gallon and but the Mollies in there, and then you can get Guppies for the 12 gallon.

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50 Bowfront, 2 Acei, 2 Yellow Labs, 1 Orange, 1 Albino, 2 Blue African Cichlids
30 Gal, 3 Fantail Goldfish, 1 Black Ryukin, 1 Common Pleco
20 Gal, Mollies, Platies, Cories, Algae Eaters
15 Gal, Swordtails, Balloon Mollies, Rasboras
10 Gal, 2 Knight Gobies
10 Gal, 2 Bolivian Rams
1.5 Gal, Male Betta

Oh,okay thanks.