Older Guppies killing newer Guppies

[Mecha Ghidrah]

I have looked all across the internet for answers but this case seems to be unique to my tank. I have a 10 gallon tank with 3 male fancies, 2 Gouramis and 2 cories. This weekend I decided to add 3 guppies (1 female and 2 males) and a plant (anachris).

The first night and day the new guppies seemed to be settling in fine with their New tankmates but on Monday morning I awoke to find two guppies dead and the female barely alive. My old ones were fine except for a rip in one's fin. Came home to find the female dead.

This isn't the first time either. I tried to introduce 2 guppies (one female and one male) and they suffered the same fate with them being alive a few days and then mysteriously die a few days later (the same guy as before had a ripped fin). At the time I thought it was a bad stock of guppies.

My established guppies are thick as thieves and never really fight. Help please.

 

[Pamiam]

You answered your own question...you have "established" guppies.

General rule of thumb:
Guppies are notorious for not being kind to each other. It is usually suggested 3 females per 1 male guppy. Males are very active breeders, if you only have 1 female to 4 males...you just gave her a death sentence.

Also are you aware, the opposite side of the coin....if you have 1 female who is pregnant, she can give birth to young every month...even without a male. Females can store sperm up to a year and fertilize their own eggs.

Also a 10 gallon tank does not give fish any room for hiding.

 

[Matt68005]

yeah a new fish in a tank full of horny males....bad idea. Guppies will chase her to death. Rule of thumb is 1:2 or 1:3 male to femal ratio

 

[mrvincent]

You can try to tell your fish to not attack tank mates.

 

[Mecha Ghidrah]

Thanks for the advice guy's, guess I'll just have to stick with these 3 as 9 females is way to much for my tank (and all the babies).