# Why Is My Guppy Being Aggressive With The New Fish



## bettaowner101 (Nov 13, 2009)

Before Sunday, I had 2 fish in my 10 gallon tank, recently upgraded to a 10 gallon from a 5 gallon. So, before Sunday I had a Female Dalmation Molly and 1 Yellow Fancy Tail Guppy Male. On Sunday, I went out and bought 2 balloon female mollies and 2 male fancy tail guppies. Ever since I have added these new fish in, the Yellow guppy has been chasing the new fish and trying to bite them.. Is this normal behaviour? When I had just the 2 fish before, the Molly was usually the more aggressive one but now it is the other way around. The tank temp stays at 78F and it is filtered with a Power Filter. Any ideas why my fish is doing this?


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## redchigh (Jan 20, 2010)

Fish have personalities. You have a aggressive guppy apparently.


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## Curt (Jan 13, 2011)

bettaowner101 said:


> Before Sunday, I had 2 fish in my 10 gallon tank, recently upgraded to a 10 gallon from a 5 gallon. So, before Sunday I had a Female Dalmation Molly and 1 Yellow Fancy Tail Guppy Male. On Sunday, I went out and bought 2 balloon female mollies and 2 male fancy tail guppies. Ever since I have added these new fish in, the Yellow guppy has been chasing the new fish and trying to bite them.. Is this normal behaviour? When I had just the 2 fish before, the Molly was usually the more aggressive one but now it is the other way around. The tank temp stays at 78F and it is filtered with a Power Filter. Any ideas why my fish is doing this?



My female guppy likes to be king of my tank. She will chase all the other fish around when to come into her area. She has taken over my volcano and its kind of funny to watch her come in and out of the vocano and chase the males out. She hasent been to the point of biting the others just chasing. at this point.


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## bettaowner101 (Nov 13, 2009)

redchigh said:


> Fish have personalities. You have a aggressive guppy apparently.


Yes, but I kind of find this very odd... Before I got the new fish, this guppy was NEVER aggressive, the Molly was. Do you think the Guppy is letting the fish know that he is boss? lol


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## bettaowner101 (Nov 13, 2009)

Curt said:


> My female guppy likes to be king of my tank. She will chase all the other fish around when to come into her area. She has taken over my volcano and its kind of funny to watch her come in and out of the vocano and chase the males out. She hasent been to the point of biting the others just chasing. at this point.


Lol, that's cute!  And before I got my fish, the guppy was NEVER Aggressive towards any fish.


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## Ma xiong (Oct 11, 2010)

he might be aggresive because
some guppies claim territories
he might chase them cuz there in his territory


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## LasColinasCichlids (Jan 4, 2011)

bettaowner101 said:


> Before Sunday, I had 2 fish in my 10 gallon tank, recently upgraded to a 10 gallon from a 5 gallon. So, before Sunday I had a Female Dalmation Molly and 1 Yellow Fancy Tail Guppy Male. On Sunday, I went out and bought 2 balloon female mollies and 2 male fancy tail guppies. Ever since I have added these new fish in, the Yellow guppy has been chasing the new fish and trying to bite them.. Is this normal behaviour? When I had just the 2 fish before, the Molly was usually the more aggressive one but now it is the other way around. The tank temp stays at 78F and it is filtered with a Power Filter. Any ideas why my fish is doing this?


Guppies are nippy fish, and when there is a group of them, they tend to argue until they find their pecking order. Give it a couple of days and the guppy should settle down as they all figure out who is running the group. 

Watch the female mollies though, as the guppies also will try to mate with them. The guppies will nip and aggrivate the female mollies trying to mate with her which in turn can cause the female mollies great stress. But since you have 3 and 3, you should be okay. If the guppies aggrivate the mollies too much, consider adding another female molly to spread out the chasing and nipping. Or buy a tank divider and seperate the female mollies from the male guppies. A general guideline for them is 1 male for every 2-3 females.


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## bettaowner101 (Nov 13, 2009)

LasColinasCichlids said:


> Guppies are nippy fish, and when there is a group of them, they tend to argue until they find their pecking order. Give it a couple of days and the guppy should settle down as they all figure out who is running the group.
> 
> Watch the female mollies though, as the guppies also will try to mate with them. The guppies will nip and aggrivate the female mollies trying to mate with her which in turn can cause the female mollies great stress. But since you have 3 and 3, you should be okay. If the guppies aggrivate the mollies too much, consider adding another female molly to spread out the chasing and nipping. Or buy a tank divider and seperate the female mollies from the male guppies. A general guideline for them is 1 male for every 2-3 females.


Thanks, the guppy bothers the Mollies but not as much as the other Guppies.


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## LasColinasCichlids (Jan 4, 2011)

bettaowner101 said:


> Thanks, the guppy bothers the Mollies but not as much as the other Guppies.


Yeah, they are just trying to establish a pecking order, nothing to worry about. And guppies tend to "play" and it can look like chasing and nipping and sometimes like dancing.


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