I found a sword tail fry with my guppies.

So I have a batch of over 40 fry in a breeder box, and I check them out today, and I see ONE fry that has a swordtail. Like the top of his back fin..looks just like a swordtail...Which through my research, Guppies and swordtails can't mate. But I have had ONLY pregnant female guppies in my tank..how can this be? Here is the best picture I could get

 

Is it maybe a deformity or perhaps the lower part of his tailfin was nipped off - resulting in it looking like a swordtail?

 

When I look at it up close, it looks perfect. Does not look like its nipped. I put them in a breeder box immediately after being born. so I mean It's a possibility. I guess I'll find out when it grows

 

Is it maybe a deformity or perhaps the lower part of his tailfin was nipped off - resulting in it looking like a swordtail?

This ^^^

 

It's not a cross between guppy and swordtail. It's just a guppy but with a deformed tail. That does happen from time to time.

Btw, topsword guppies do exsist as well. But every topsword, lower sword and doublesword guppy will be born as a normal shorttail. The extended fin rays will develop later on. If a guppy already shows at such a young age something like in your photo, it is a deformed fin or a damaged fin.

 

Got it!! I just looked this morning and more of its tail is nipped. So probably not any kind of sword tail tbh. But they are with other guppy fry. Are there too many in the breeder box? I just separated half into another breeder box this morning, hoping that will lower the agression.

 

Got it!! I just looked this morning and more of its tail is nipped. So probably not any kind of sword tail tbh. But they are with other guppy fry. Are there too many in the breeder box? I just separated half into another breeder box this morning, hoping that will lower the agression.

You could try to separate them and see if they'll grow up without any fights.

 

You mean put them in a totally different tank? I have some 6 week old fry in a 37 gallon. Should I put them in there? The young fry are about 2 or 3 weeks old.