A pregnant guppy can be identified by the following characteristics; it’s recommended to observe a combination of indicators for confirmation:
Changes in Abdominal Shape
From the side, the abdomen gradually shifts from a "smooth, rounded curve" to a sharp-angled "square" or "trapezoid." Right before giving birth, it may even appear translucent, with faint outlines of the fry’s eyes visible.
When viewed from above, the abdomen swells into a diamond shape, with its widest midsection exceeding twice the width of the head—a distinct difference from the rounded belly of a well-fed fish.
Evolution of Gestational Spot Traits
The color of the gestational spot above the anus deepens over time:
For regular varieties: light gray → deep black
For albino varieties (with red eyes): orange-red
Just before delivery, the spot expands in size, revealing dense, clear eye spots of the fry inside.
Changes in the Genital Pore
1–2 days before birth, the genital pore protrudes to form a transparent "pointed tip," creating a right angle with the abdomen.
Some individuals may show slight redness or swelling around the anus.
Abnormal Behavior
Hiding in aquatic plants or corners and refusing to eat.
Clumsy swimming with unusual postures (such as tilting the head upward or rubbing against the tank walls).
Some may become aggressive, attacking other fish, or even attempting to jump out of the tank.
Note: Distinguishing Between False Pregnancy/Abdominal Dropsy
In a true pregnancy, the swollen area is concentrated in the mid to rear part of the abdomen; with dropsy, the swelling is wider at the front and narrower at the rear.
If the abdomen remains square and swollen 24 hours after stopping feeding, pregnancy can be confirmed.
(Observation tip: Check in the morning before feeding to avoid confusing the condition with a full belly.)