My Female Molly's Tail Is Bent Downwards And She Doesnt Seem To Be

[minla]

hello,
im fairly new to fish keeping and had a few issues in the beginning.. ive had to contend with two bouts of ich to which i lost virtually all (10) my Moscow Blue guppies and one neon tetra. (2 months ago I was gifted 4 mollies (3 boys, 1 girl) and 2 Platys (both girls). they all seemed to hold pretty well until now. they all seem pretty happy with each other. i have a 108 ltr tank and they share the space with 11 neon tetra, 3 guppies, and one betta. one of the male mollies seems pretty aggressive though and had been trying to mate with the female.  after the second bout of ich ive been keeping an eye on them every night before i get to bed. they were all doing very well, including the female and were very responsive everytime i went near the tank.
in the last few days, ive noticed my female molly looking pretty down. her tail fin has a small tear (DO TEARS HEAL OVER TIME?) and the tail itself seems bent downwards a little. I dont have a separate tank, so i separated her from the rest using a small netted basket, since i thought maybe the male may have gone at her too hard perhaps? (this sounds so wrong but i cant put it any other way!) i feel so bad for her. Im a vet by profession, but vet college never prepared us for sick fish! i need help! We both do!!! 

 

[DeanoL83]

Hi and welcome!  Fishkeeping is a wonderful hobby, but some important things to get right first!
 
How long has your tank been running for?  Did you cycle it before adding fish?
 
Have you tested the water using a test kit?  If so, could you give us some numbers for the ammonia, nitrite and nitrate please?
 
Also, livebearers basically do two things all day: eat and breed.  The males will relentlessly chase a female around a tank to breed all day.  Because of this, it is highly recommended to have a ratio of 1 male : 3 females.  Unfortunately, you have your ratio the wrong way around.  With three males and only one female, that poor female will never get a break and will probably be super stressed.  
 
You have two options:
a) find a new home for the female molly
b) buy 6 more female mollies.
 
Hope I don't sound too negative!  Many of us here have made many mistakes when starting out.
 
I'm not an expert, but we would need to know more about your tank before we can tell you exactly what's going on.  

 

[Blough]

Welcome to the hobby!

I agree with what DeanoL83 said, but have some things to add. Bettas are not community fish, they prefer living in a solitary tank. They can get aggressive towards other fish with bright colors or big fins. It might be the betta attacking the molly that is causing the tears in her fins. Most tetras are nippy and can hurt the betta's delicate fins. I would suggest either getting a 5-10 gallon aquarium for the betta alone, or finding another home for him.
I wish you the best of luck.
Edit: Grammar