You can determine if a guppy is pregnant by observing the following comprehensive characteristics, combining multi-dimensional judgments of morphology, behavior, and physiological changes:
1. Morphological Features
Changes in Abdominal Shape
After pregnancy, the abdomen appears square with a pointed front and a broad rear when viewed from the side, and triangular or box-like when viewed from above, with an overall obvious enlargement.
The anal fin will gradually change from round to smoothly square, especially more noticeably before delivery.
Color and State of the Gravid Spot
Black-morph guppies: The gravid spot is pale yellow or transparent when unfertilized, and turns deep black after fertilization.
Albino guppies: The gravid spot is pale yellow when unfertilized, turns orange-red or orange after fertilization, and the eyes of the fry can be seen before delivery.
The gravid spot is located at the junction of the abdomen and the tail. Its area increases and its color deepens when approaching delivery.
2. Behavioral Performance
Abnormal Activity
The guppy swims clumsily with an increased range of body swings, often staying close to the bottom of the tank or hiding in concealed places such as aquatic plants and filters.
Before delivery, its appetite decreases or even stops eating, and it may attack other fish that get close.
Changes in the Genital Pore
Before delivery, the genital pore protrudes into a small sharp angle, and a long strip-like sag forms on the side of the abdomen.
3. Other Auxiliary Judgments
Changes in Excrement: It may excrete thick black feces before delivery.
Time Calculation: If the color of the gravid spot changes after observing that male and female fish are kept in the same tank, delivery usually occurs about 30 days later.
Notes
It is necessary to rule out the interference of "overfeeding". It is recommended to observe the abdominal shape before feeding.
If multiple of the above characteristics are found, it is advisable to isolate the female fish in advance to prevent it from eating the fry.