Is my mosquito minnow pregnant? How to know if your fish is expecting?

A female guppy will develop what is known as a "gravid spot" when pregnant. It is triangular and located near the vent on the abdomen under the tail. It will get bigger and darker as she nears spawning. If she was skinny when you got her and she is that big now, she is pregnant. They are live bearers, so the fry (baby fish) will need cover (places to hide) or they will be eaten. It is best to separate them into grow out tanks.

Thanks for reaching out about Black molly, but a good photo would help. White spots can be infections, parasites, over-active mucus cells, and some other conditions. If the white spot is the anus and is slightly protruding, she could be gravid but maybe intestinal parasites. If concerned, seek the attention of an aquatic veterinarian. Good luck.

She appears to have eggs given her girth. There are also some vertical bars on her side that indicate she may be ready to spawn. If possible, check underneath for a pronounced white dot. This is further proof that she is ready to spawn.

She looks like she may be pregnant. A female platy will become quite large when pregnant. Gestation lasts about 28 days. When she's ready, she will swim to a quiet part of the tank and give birth. The fry are fully developed and able to swim. If not removed soon, they may get eaten by the mother or other fish in the tank.

You need only provide plenty of space, clean water and a quality flake or pelleted diet. Male goldfish will develop white dots on the fins and gills when ready to mate. He (they) may chase her around and bump her stomach to get her to spawn (lay eggs). When she is ready, she will seek out planted or quiet area of the tank and spawn. The males will then release sperm to fertilize the eggs. The eggs will need to be removed to a separate tank to prevent them from being eaten by the adults. The eggs will need to be kept at a certain temperature and in clean water until they hatch within a week's time. Afterwards, you will have MANY fish to care for and feed. This can quickly become an overwhelming task and should not be undertaken without serious forethought. You can read more about goldfish breeding here: http://thegoldfishtank.com/goldfish-care/breeding/goldfish-breeding-breed-goldfish/

Thanks for reaching out and including photos. Coeloms (abdomens) are swollen, but unable to determine if eggs. Often when it is time to spawn, the vent becomes slightly everted. An ultrasound would be the only way to truly determine if eggs are in the abdomen. Good luck.

Beta fish lay eggs and she would need a male to then fertilize those eggs after she lays them. Breeding betas can be very work intensive. Here is a link with great information: fishkeepingworld.com/breeding-betta-fish/ As the babies get bigger, they can graduate to larger food. The babies will mature and need to be separated around 3 months of age. The females can stay together but all the males will need to be separated. Breeding betas requires a lot of tanks/space. I recommend to connect with a local aquarium store and find out if anyone has first hand knowledge. I hope this helps and please feel free to post any additional questions.