I’ve been looking into mangrove snakes and thinking about getting one. I have pretty much everything i need before i get the snake apart from the enclosure which I’ve seen mixed results for across the internet. So how big of an enclosure would you need for a 8-9ft female? and also how would you set up the enclosure?
Thanks for the help in advance.
So first off I would like to welcome you to the community! I can’t wait to see you around more 
Back to business. So for an 8-9ft female, the absolute bare minimum I would recommend is a 4x2x6 foot enclosure. However for long term care I would suggest getting a 6x2x6 foot enclosure to provide the ideal conditions for one. I haven’t kept them though so this is just off of my knowledge of the species.
Anyway, that is a really adorable skink!
I know that @auriea has a mangrove snake (though I’m not sure precisely what species), so I’m tagging her so she’ll see this. Hopefully she can give you some ideas.
Thanks for the tag @jawramik
My Mangrove is also a Melanota. He is a wild caught 7 foot adult.
A good thing to keep in mind is that while they are very very long snakes, for their length they are actually quite small. Nugget is 7 feet long, and yet he can fit his whole body into a decently sized tupperware container with some room to spare.
So, unlike other large colubrids like bull snakes, indigo snakes, etc. The space they actually fill with that footage is considerably smaller than what you may expect. For example, my jungle carpet, who is going to max out at probably 5ft, is most likely going to be twice the size of Nugget when he is fully grown despite being two feet smaller. So he will take up more space, and therefore need more space by mass alone.
With that being said, they are fairly active snakes at night. They would benefit from a larger environment if providing that is possible to allow them to stretch and express their natural behaviors. Their energy level should be a big part of choosing their enclosure size.
My recommendation would be a 6lx3wx2(or)3h minimum, for longer term care. Ideal would be 8lx3wx3(or)4h
But whatever you choose, the most important thing is that first and foremost, you feel capable financially and in ability to FILL that enclosure with enough enrichment to engage their minds day in and day out. If you buy the biggest enclosure and don’t pack it full of stuff for them to explore, then you will still end up with an unhappy snake.
Mangrove snakes also benefit greatly from water features. If you can incorporate a pool into your setup that your snake can swim in if they want, with plenty of land available still, then they will be better for it.
Last thing to keep in consideration is that mangrove snakes are very reactive. If this is an animal that you hope to be able to handle (sparingly), and intend to work with, then during the time in which you work with that animal and set it’s foundation, it is recommended instead by Kevin McCurley to keep them in a terrestrial setup for cleaner management and less stress to the animal. Ideally the goal would be to graduate to the full arboreal setup eventually.
A personal disclaimer is that while this is my opinion and i do stand by it, i myself am not yet at that standard myself with Nugget due to personal reasons and the unexpected abruptness of my acquisition of him.