The water.
You don't. Your fish should naturally make it when it feels it is ready to breed.
Yes, fish can get pregnant. They can be live bearers (have them like a women does) Or they can lay eggs which they hide in a nest the build around the tank
crow yes build nest
penguins build their nest in summer
Many animals build nests, including most birds, and some mammals, fish, and amphibians.
Normally, they build their nest on a corn plant
When bird find mate they will build a nest
No. Emperor Penguins and King penguins do not build a nest.
If a doe has a false pregnancy she will build a nest.
the male betta fish makes the nest.
bees wasps build nest anywhere they can find shelter.
Bluebirds sometimes build more than one nest, as a diversion to predators.