Yes but only for eating purpose
Crabs have many different species, like any other animals, they love to mate and so there are millions around the whole world.
No, just like us seahorses mate with their own kind.
No, Betta fish are aggressive toward any other fish they see. They cannot mate.
it eats crabs, clams, and any other kind of tiny fish.
Plants, Crabs, ETc...
most likely to mate it would be awfully hard to get privacy any other way.
Mollys can breed with any other type of molly fish
crabs will eat any kind of meat because they are always hungry
Simple answer is yes. Guppies mate and produce young under almost any reasonable conditions. The presence of other fish will not bother them at all provided the other fish are not predators and the guppies under pressure for survival.
No you cant unless its the father because the other fish will fight with the mom so keep any fish away besides the dad she had to mate with
to protect them from any other crabs or people stepping on them
Crabs will eat any dead fish they can get their claws on. There isn't much they won't eat. Answers.com has a good article on the crab, and it includes information on its diet.