The female will have a black patch at the back where the babies come out of ,sometimes she may keep going to the top as she will be running out of breath alot but sometimes we dont notice and she may have a square belly at the front also if the male hangs around the female alot (underneath her)then that means she is ready to give birth soon because as soon as the fri(babies) are born then he will try and eat them ,so if you see any of them signs quickly buy a nursery tank and pop her in it.
By performing an experiment
Danios are egg layers and can not get pregnant.
If you look at there bottom fin the males have a fin that sticks strait back where females are fan shaped.
You wouldn't ever be able to tell this, because carp fish do not get pregnant. Pregnancy implies carrying the young internally, which carp do not do.
Pregnant fish may appear rounder or have a swollen belly. You can tell if a fish is expecting offspring by observing its enlarged abdomen and possibly seeing small, developing eggs inside.
Goldfish of any type are all egg laying fish which means that they do not get pregnant
With a guppy you need to look at the gravid spot. This is a dark spot in the fish's belly. A large gravid spot indicates the fish is likely to be pregnant. You can tell how pregnant the fish is by how large the spot is. Sorry I have no experience with other species.
If it has ever been anywhere near a male it will be pregnant (Gravid). It is very difficult to get a virgin livebearer. They can be gravid at 3 or 4 weeks old.
To determine if a fish is pregnant, look for signs such as a swollen abdomen, changes in behavior, and a darker gravid spot near the anal vent. Pregnant fish may also exhibit increased appetite and aggression.
Orandas, or any other type of goldfish are egg laying fish, so they do not get pregnant
Mollie and vanessa are very close. frankie and vanessa. rochelle and mollie are close to. you can tell this from all the photos.
Black moors are a variety of goldfish which are egg layers so they can't get pregnant.