Fish that lay eggs show almost no visible signs of pregnancy, although those who bear live fish start to show a definite abdominal bulge, as well as a general lethargy and signs of secretiveness in the aquarium. In an aquarium with several fish, it is fairly obvious which fish is pregnant, because the rest of the fish stay in their normally slender shape.Continue Reading
In addition to their abdominal swelling, some of the species of live-bearing fish develop a gravid, or a dark spot near their anal fin. The male fish fertilizes the eggs while they are still inside the female, and the young fish are born live, swimming on their own in a short amount of time. Fish that give birth to live young include mollies, platys, pike, swordtails and guppies, among others.
Mother fish that are about to give live birth become increasingly reticent, hiding among the castles and foliage in the aquarium. They are looking for a safe spot for the birth to take place without the dangers of prey nearby. As the mother fish continue to grow and approach birth, they increase in size but lose energy. They often swim slowly and cut back on their eating. These changes indicate that the mother will give birth soon.Learn more about Fish
Two major considerations in breeding GloFish, a genetically modified variety of the tropical zebra danio fish, are to keep the eggs from being consumed by the fish for food and to make sure they are not swept into the tank's air filter. Zebra danio lay eggs that do not adhere to a surface, so protecting them is the primary goal in successful breeding.Full Answer >
While many fish species are oviparous, not all are; some fish species are ovoviviparous, meaning that eggs are gestated and hatched inside of the female fish's body and fish fry (babies) are born live. These live-birthing fish are commonly known as livebearers.Full Answer >
Common carp eat insects, aquatic worms, earthworms, snails, crayfish, rotifers, mussels, water plants, algae, dead plant parts and fish eggs. They skim the bottoms of bodies of water, sucking in food and mud then spitting out what they don't consume. The uprooting of plants and fish egg consumption harm other fish populations.Full Answer >
Bony fish have a variety of reproductive strategies, but in most species two separate sexes release sperm and eggs into the water, and fertilization occurs externally. Parental care is quite rare, but seahorses and a few other species do care for their young. Some bony fish change sexes depending on conditions, while others fertilize eggs internally or even birth live young.Full Answer >