As there was a place near my settled home with 4 squids, I decided to build a glass enclosure below the pond they were in, and then break all the soil beneath the water to entrap them in an underground glassed enclosure, so I now have a Squid Aquarium.
They seem to stay there between sessions of playing which is good.
However if killed I believe they will not respawn there.
Then my daughter discovered another lot of squids in deeper open water, so I jokingly said let's transport them to the Squidarium. Well after some thought I actually moved them around 100 to 150 blocks away and into my Aquarium. It should have ended up with 7 squids in my aquarium but alas I accidentally squashed one under sand while moving them.
I dug a channel all the way to my aquarium, but the main problem is that squids go to the lowest point in any water and then randomly swim at that level, but I needed to move them slightly uphill. I put half blocks where I wanted to make them go up one block, and then sort of go in the water and pushed up against them until they jumped up. It took me over an hour to move them but I got there in the end.
Now a 6 squid aquarium, you can dive from the diving board into the water, swim with them, or view them from behind the glass.
I'll add some pics soon.