Platies harassing Betta

Question
Good evening,

I have a 10 gallon tank which housed my betta.  He was a healthy fish but seemed somewhat languid and bored and I was advised that he would benefit from the stimulation of having a community tank.

Last week I added 4 platies.  I got all males so I wouldn't have to deal with over population.  I was advised that, as long as I had more than just 2, they would get along well.

Tonight I noticed that my betta was not looking well.  He was losing color along his belly and "pacing" in front the the aquarium, frantic, odd behavior for him.  I noticed him "submitting" space to any of the platies that came his way.  It also appears that his pectoral fin (he only has one) may be damaged.

The platies are in constant motion and seem like they are always jostling one another.  I'm thinking they may be stressing him out.  There may be too many of them, they may be too active, he may not be able to have his own space with them darting around and they may be picking on him as well?  He has never been aggressive to them since I added them, he seemed happy to have some companions.

Do I a) have too many platies, or b) have too many males?  Should I take 3 of them back and just have 1 male?  Should I exchange them all for 2 or 3 females?  Should I have 1 male and 1 or 2 females and just take my chances with babies?  I'm pretty sure my LFS will be willing to work with me on this issue, I'm just not sure which direction I should go.  I would give the betta his entire tank back to himself, but he seemed so interested to have other fish with him.  Any thoughts?  For tonight I have moved him into a 2 gallon bowl just to give him some rest.  This is only a temporary solution as the tank really belonged to him first, and it's getting too cold to keep him in a un-heated container.  Thanks so much.

Answer
Hi Joan,
The situation here I believe is the male platies are indeed harassing the betta. Male platies have a strong instinct and drive to be boisterous and breed all the time. And often any fish will be their target for letting out this overpowering instinct.

It would probably be better if you swapped the platies for a different species of fish. Such as any small and peaceful non-livebearing species. small Tetras, Rasboras, White clouds, ect..

The only other way I think this might work out somewhat is if the male platies had females to chase. But with four males you'd need at least eight females to limit the chance of any one fish being made miserable. When platies are kept in pairs (1 male and 1 female) it always happens that the male will make the female miserable all the time with his chasing and nipping.

If you ever have females at any length of time you can certainly have the chance of babies being born.

Again I think your best bets are switching to a different species.

I hope this helps and best of luck!
Karen~