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I have a guppy that is 3 inches long. It has a big colorful tail, but im not sure if its a girl or a boy... His or her body is a blueish brown shade.



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Last edited by Adam at 16-Aug-2005 09:54

Ah, luckily you've picked a fish in which the male has an external sexual organ. That makes sexing it quite easier.

In terms of guppies, swordtails, mollies, platies, and a number of other livebearing fish, the males sport what is known as a "gonopodium" while the females do not. The gonopodium is used to internally fertilize the females. To find it, you just look at the anal fin; it is the single fin on the underside of the body (the paired fins are known as ventral or pelvic fins). If it is long and thin, it's a gonopodium and you've got a male. If it is rounded like a normal fin, then you've got a female.

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The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.

Stripes,

You can also read This Sticky from the Livebearer Lane Forum.

Ingo

EDIT: Guppies get 3 inches long ?

Last edited by LITTLE_FISH at 16-Aug-2005 11:21

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Proud Member of the New Jersey Aquatic Gardeners Club

Yup, he is right. But there is another way to tell the difference in guppy's. Males will (usually) have much longer cuadal fins (tail fin) than the females. Not all the time though, so then you will have to go back to the ganopodium to determine the sex of the individual like said in the above post. Older guppy's are easy to tell apart...females will be large and males often smaller.

males have a pointed lower fin, where the females will have a fan. also now or days, guppy females are become just as colorful and longer tail, like the males, so dont always base it off of that.

If your guppy is 3 inches long, it must be a female, due to the fact that males only reach about half that length, but females will occasionally grow that big.