• One Moonpool
  
• A path between where your moonpool and where you want your cuddlefish
  
• A propulsion cannon (NOT A REPULSION CANNON)
  
• A door keeping your cuddlefish from swimming to your moonpool and exiting the base (If you want him swimming throughout your base)
  
• An alien containment with a hatch

To start off, your gonna want to take your freshly hatched Cuddlefish outside. This lets you be able to interact with him. MAKE SURE YOU SET HIM TO FOLLOW YOU.

Bring him to your moonpool. NOW FOLLOW INSTRUCTIONS VERY CAREFULLY FROM HERE ON OUT. Your gonna want to use your propulsion cannon to pick them up (Point it just outside their play hitbox) and swim into your moonpool. (dont use the ladder.)

Keep holding him with the propulsion cannon until you have him in the place in your base you want him to be. Now, unequip your propulsion cannon. DO NOT LAUNCH YOUR POOR CUDDLEFISH. ask him to stop following you and place a door between your cuddlefish and your moonpool(s). Now your cuddlefish is safely secured in your base! but do you feel bad that your cuddlefish is alone in your base? then follow the next step to find out how to keep him in alien containment without losing the ability to play with him!

Ask your cuddlefish to follow you again and bring him to your alien containment. Get into a position where you are looking into the alien containment but can still play with your cuddlefish. Using his play animation temporarily disables his hitbox, and by activating this animation, he will swim from his position into the alien containment. When he is done with this animation, he will be in the alien containment. Make sure to fill the containment with fish or other cuddlefish so he can have friends in your base! If you ever need to get him out, you can glitch him out with the same trick.