Moving him into a 10 gallon, everything I read said a 10 gallon should be good for a single crayfish (which is what I believe he actually is).
Now to express how I felt this morning after Captain apparently had a lot of fun during the night.
At least three of four live plants were uprooted, one of which was floating around the top. The others he will pick up, move around, and chew on from time to time. The plastic plants had all been shoved into different locations and turned at weird angles, which made little sense. New piles of gravel had been created, leaving some spots bare. He tends to alter these whenever he stumbles upon them.
So now here I am planning his 10 gallon long tank, thinking of how I can make it beautiful and secure for him. I want to fill it up mostly with water, so I plan on adding rock shelves for him to climb on top of to assure he doesn't drown. I will also be crafting several natural looking caves and hides, and the plants will all be placed so carefully to provide cover and also look good to the human eye.
But it won't stay beautiful, will it? XD I'll have to tether the plants down, it would seem.
Little monster is lucky I love invertebrates so much.
And no worries, he will never be housed with fish unless it's for the purpose of giving him a snack!