I have a 5g planted betta tank and just received 2 assassin snail to help get rid of the baby snails that somehow entered my tank. One looks to be sexually mature and the other looks like a baby still. Should I put them both in the tank or should I re-home the second one so that I don't end up with an over populated tank? I have 3 ghost shrimp in the tank also so I am very concerned about having multiples and them ganging up on the shrimp. Is there any way to sex the snails? I have been researching it and the answer seems to be no. I think the best option is to re-home one of them and keep just one in my tank but I would like to know other peoples opinions.
It's hard to sex snails until you find babies, and it seems you realize that assassins are male-female and require both sexes to breed. Assassins reproduce by laying/fertilizing one egg at a time under the sand. The baby snail lives there eating tiny matter until it grows up and comes out of the sand. You shouldn't be overcome!
Also, they will never catch shrimp. Shrimp are too fast and can swim up/away very quickly.
Conditions for breeding need to be perfect. There needs to be a steady, plentiful supply of food for them. They move quick in groups, it's pretty fun to watch, but if the shrimp is able to get caught and "stuck" by the prodding thing then it's natural selection! Shrimp can move quick enough to survive.