How to add new fish or mobile inverts to the aquarium and keep others safe on going.

Make up something like this!
I use plastic bottles like a one and half litre or two litre drink bottles, for example, a coke bottle!
Cut the top off then make holes in it to allow oxygenated waters to pass through.
You could use a drill, but it will make sharp edges to the holes, I use a soldering iron, the melting forms an edge much smoother.
Then attach via holes, then line through those holes and tie a weight to the base, not in it, out side the container, then a fishing sinker on line to hang over the edge of your tank so the container does not sink allowing the creature to escape far to early.
This way is so you can acclimatize the new creature to the tank by all seeing it and it seeing them and no one can hurt each other.
Then just as lights are about to go out, add new life to tank.
I have also been using these containers for many year to house life for extended lengths of time for many reasons,

container


weight to stop container from sinking