HELP!! Molly are acting weird

[QueenBee]

So I have a 10 gallon tank with 2 Molly, one silver and one dalmation. Yesterday I introduced a black molly to my aquarium and my silver molly instantly became aggressive towards the black one!! It follows the black one hitting it or nipping it's fins constantly!!! The poor new one cannot get a break! Then I began to think the dalmation molly was pregnant because of the way it was acting and possibly the silver one was just protecting it. Well I started feeling horrible for the poor new one and removed the silver molly from the tank all together because he just wouldn't let up. It even began to get black spots and the fins were turning black on the tips and that scared me. Can anyone give me some advice on what to do about these three or possibly some information on why this is happeneing?? I've had many aquariums before, but just boring old gold fish. New to the whole "tropical fish" environment and have no idea what's going on. Lol Thanks in advance!

 

[NickNaylor]

I have read that mollies can be aggressive - this doesn't sound like anything more than that. What do you have going on in your tank? Do you have enough places for everyone to hide, if needed?

 

[QueenBee]

Yes, I have two actual decorations with hiding spots in them and then lots of plants. I'm planning on getting taller plants the reach the top of the water as well.

 

[NickNaylor]

Yes, I have two actual decorations with hiding spots in them and then lots of plants. I'm planning on getting taller plants the reach the top of the water as well.

Well like I said, none of this sounds particularly unusual. I guess one of them could be pregnant - sort of difficult to say one way or another without a picture, and frankly I don't consider myself experienced enough to "diagnose" pregnancy anyway.

I wouldn't worry yourself over it. There's probably some social "stress" from the introduction of a new tank mate. My guess is that it'll sort itself out with time once everyone figures out where in the hierarchy they fall.

 

[Delapool]

Hi, just an additional thought to above. The black markings you describe has also indicated chemical burns in other tanks eg ammonia. If you have a water test kit could be worth checking ammonia.