It is very early days and he is scared. The hissing etc is just fear that you are going to hurt him and are invading his territory (which he hasn't fully settled into yet) and at this early time a hand in the cage will feel like an invasion.
Although he has been tame he has not yet got used to you personally or built a trust bond. So it's a case of taking it slowly. Believe me he is more scared than you are.
The other thing is with a top opening cage, your hand is coming from above and as prey animals they fear anything coming from above. Some hamsters get used to this, some don't.
I think what may have really upset him is you moving things around in his cage. They really don't like that! Especially in the early days.
General advice is, as you have done, leave them alone to settle in for two or three days. But after that don't clean the cage for a couple of weeks or change things or move things, because they are adjusting and scent marking everything.
It can take a good two weeks for them to settle in a new environment and even if it's the same cage, it's a different place. Even moving a cage into a different room or a different position can really set them back for a couple of weeks.
Water bottles can be a total pain - just adds to the stress! Maybe you need a different water bottle. It's always good to have a spare as well in case one stops working.
For now I would just talk to him through the cage. Say sorry in your sorriest voice (I swear they respond to tone of voice and understand you!) And tell him he's clever and lovely.
To make up for the minor disturbances and frights, you could hide a few treats in his cage for him to find to distract him, but do it when he's asleep.
For now I would suggest not putting your hand in his cage except to put out food and water when he's asleep. If after a week he seems more settled and you want to try handling him - it is better done out of the cage than in it. They behave completely differently outof the cage. Inside the cage is their territory.
To get him out you could let him walk into a tube with a treat at one end then put both hands over either end of the tube and lift him out like that. Wear gloves if you're nervous so you don't drop it! Next to the cage you need something to put the tube down into straight away. Eg a large box or plastic bin. If it's large enough you could use that as a taming bin, or you could just carry him to the bathtub or a playpen area in it and let him run around in there and occasionally stroke him or let him run over the flat of your hand on the base of the bath/playpen. So he gets used to your presence, scent and realises you aren't going to hurt him.
If you have a hamster ball it could be easier to lower that into the cage with a treat inside and let him walk into that. Then you can just pop the lid on and carry the ball to where you want to let him out.
For now best not to tinker with his cage or move things or take things away. Adding something new can go down well as long as it doesn't mean moving things around.
Take it slowly and I'm sure he'll soon be lovely and tame with you.
How is the water bottle attached? Some people use industrial strength velcro to attach a bottle inside if it isn't sitting quite right (assume there's a bottle hole with that cage).
I find these bottles very good - they don't drip or leak and they let the water out well. Well hardly ever drip! I get two at a time to save on postage.
You won't be able to use the clip as that's for a barred cage.
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