Aggressive female Guppy!

[guppymonkey]

I put my pregnant female guppy into my 5 1/2 gallon tank until she was ready to give birth and now when I tried putting her back into the 20 gallon she became very aggressive towards the female in that tank. As soon as she went into the 20 she immediately started chasing the other female and wouldn't leave her alone!

 

[snowyangel]

I have one VERY dominant female guppy in my tank too and she nips and chases all the guppies, but no deaths , its just pecking order. This Happens with most fish. Unless visible damage is being done, dont worry. Maybe add some coverage for the victims.

 

[guppymonkey]

This female is seriously trying to kill the other female guppy. Where ever the one guppy goes the older one will follow it and go for its fins. I tried several times to add the older one to the tank and every single time she went into attack mode. There are a lot of plants in the tank but the older guppy will follow the younger one into the plants to try to rip its fins off. I guess they will have to stay separated. She doesn't attack any other fish or male guppies. Its just strange.