Aggressive Sailfin Molly(F)

Hi all,

Happy New Year! This is my first time posting after lurking quite awhile!

I have a FEMALE gold sail fin Molly in a 40gal. We got her right before Christmas and she was peaceful and got along with everyone else. She is the only Molly in the tank (we got a pair but the dad died during transit from our LFS). To our surprise, she had 15 babies within a week of arriving home. immediately after she had all the babies, she became EXTREMELY aggressive toward all of my other fish. She almost killed one of my plecos fighting over an algae wafer. We have no choice but to keep her in a quarantine floater box. However, it's quite small and I don't want her to be unhappy either.

I did some research and looked through other posts (some of them even on aggressive sail fins!) but they aren't particularly helpful. The suggestions were either get more mollies - or get rid of them (aka re-home). I don't want to get more mollies unless I am fairly certain that it would fix the issue. Additionally, my tank is reaching its stock limit and for the welfare of my current fish, getting more fish is my last resort. I want to be responsible for the fish that I do buy and I don't want to put other mollies' happiness on the line just to experiment. I also want to exhaust my options before I re-home her.

Here is my stock list:

3 pea puffers
1 freshwater butterfly fish
2 abino plecos
6 rainbow fish
2 bala sharks
2 neon blue dwarf gouramis

1 figure 8 puffer (I understand that there is a debate on the brackish-ness of the figure 8. But I already have him and I love him and I want to give him a good life under the circumstances. I got this fish after the Molly fish had babies and exhibiting aggressive behavior to all the other fish listed. The figure 8 does not exhibit aggressive behavior to any fish in the tank but the Molly - before we quarantined her - try to nip at the figure 8's fins and chase him around)

Also all of the above fish are peaceful towards their own kinds and towards all the other fish. They get along great.

The baby mollies are quarantined and separated from everyone.

Water parameter is good. We test the water frequently and the tank is kept at 78F. We have a Fluval 407 with a spray bar. Tank has a drift wood and live plants with a combination of decoration that creates hiding spots. We feed them flakes and options from (live black worms/frozen blood worms/frozen brine shrimps), algae wafers/spirulina pellets for the plecos and occasional crickets for the butterfly fish. We are also observant on stress behavior.

Any suggestion or recommendations are greatly welcome!

TIA!

 

We got rid of our sailfin because he was so dang aggressive like yours.

 

We got rid of our sailfin because he was so dang aggressive like yours.

lol I wish there are more acknowledgement of this instead of advertising how much of a good tank mate they are...

 

lol I wish there are more acknowledgement of this instead of advertising how much of a good tank mate they are...

Most of my mollies have been jerky, but the sailfin was the worst! Was also bigger than most of the fish at the time as well, which i am sure didn't help.

 

I've owned mollies in the past and I agree with BigManAquatics, mollies are mean fish. Of course, there is always going to be a few that are peaceful, but IMO, they aren't a very good fish for community tanks or beginner fish keepers.
I don't personally think adding more mollies will help much, but I've never tried it so who knows?

 

If one will keep sailfin mollies, sufficient open space is important. With less open space, they tend to become more dominant in a tank. At least, that's the general behavior in smaller spaces.
If one would like to combine them with other kinds of fish in a smaller space, better choose sturdy build fish. For "most" smaller ones will be chased around by them.