Aggressive Platy: Bad Gender Ratio

[firsttimefry]

We have 3 platies.  2 are males and 1 is female. (Didn't know this when they were bought).  For a month everything was great and they joined our community tank nicely (also have a dwarf gourami, 4 neon tetra, 2 danio, two frogs).  Recently however the bigger platy male has started chasing the little male around and poking at him.  He is his constant nagging shadow.  The female has taken to hiding up in the top corner of our tank beside the heater.  Anytime she ventures down the little male gets all wiggly fins around her which I am assuming is some kind of mating routine.  The bigger male doesn't do this just harasses the other male.  Is there any way we can offset the male to male agression?

 

[the_lock_man]

Only by increasing the numbers - you can't really make the fish sit on the naughty-step until he learns the error of his ways!
 
If you were to buy 3 or 4 more females, the chances are that the dominant male would spend more of his time chasing the females, and less asserting his dominance over the other male.

 

[daizeUK]

My advice would be to rehome one of the males.  I had a similar situation with 2 males and 4 females.  Despite the number of females, the sub-dominant male was chased mercilessly every time he came out of hiding.  A year later he is a nervous wreck and now showing susceptibility to disease.  He is obviously suffering badly from the the constant bullying.  I've even tried adding another male to distract attention but this particular platy male still gets excessively bullied - I guess the dominant male just really doesn't like him!

 

[firsttimefry]

haha the timeout cave won't work eh? I think we are going to be having some fry soon as she looks huge and can see all kinds of little dots in her belly. Maybe her pregnancy is what set him off. Some serious fish drama going on.  If he doesnt calm down soon, we will try bringing a couple new females in or rehoming him.  No one in the tank seems to like him much anyways.

 

[Lunar Jetman]

My advice would be to rehome one of the males.  I had a similar situation with 2 males and 4 females.  Despite the number of females, the sub-dominant male was chased mercilessly every time he came out of hiding.  A year later he is a nervous wreck and now showing susceptibility to disease.  He is obviously suffering badly from the the constant bullying.  I've even tried adding another male to distract attention but this particular platy male still gets excessively bullied - I guess the dominant male just really doesn't like him!

 
I would say you don't necessarily need to re-home a male fish. Ideally you want at least 3 females to 1 male so in Daize's example, she has the wrong ratio too so the behaviour she experienced would be expected and adding an extra male rather than more females isn't the best thing to do either.
 
If you have the space (what size is your tank?) then follow TLMs advice and get some more females. Its never a good idea to sort out a problem between male livebearers by getting more males!

 

[firsttimefry]

We have a 20 gallon tank so a little more room I think but not a ton. Adding 4 more fish would be pushing it. I am not really sure on fish to gallon ratios and how frogs count.  I would be comfortable with 2 more fish in there max, based on how our fish act and how much space they use.  Ideally I would like to see if we could get a couple fry to live but 1) thats not likely with the frogs and 2) what if only males lived?  ...

 

[daizeUK]

I would say you don't necessarily need to re-home a male fish. Ideally you want at least 3 females to 1 male so in Daize's example, she has the wrong ratio too so the behaviour she experienced would be expected and adding an extra male rather than more females isn't the best thing to do either.
 
If you have the space (what size is your tank?) then follow TLMs advice and get some more females. Its never a good idea to sort out a problem between male livebearers by getting more males!
 

 
That's what I initially believed too.  My original plan was to get 1 male and 3 females but, livebearers being what they are, one of the females turned out to be a late-developing male!  It blew my plans out of the water because 2 males is a bad combination since one will take all the aggression from the other.  I've since been told by a livebearer expert that the 1:3 male to female ratio is only applicable for small numbers.  The more fish you have, the less it matters how many males there are.  For larger numbers of fish a 1:2 or even 1:1 ratio is fine because the males will spend time fighting amongst themselves rather than chasing the females.  So 2 males to 4 females is actually a good ratio, if not for the fact that 2 males is a bad idea.