I notice you call a RES a tortoise.. here in the US there is a difference between a turtle and a tortoise. RES are aquatic turtles, which means they live in and around water. The water level at a MINIMUM should be 1.5 times their shell length I believe. It is better to make it even deeper if you can. It is also suggested that they have 10 gallons of living space for each inch of straight shell length. They need more than "enough room to move around". They live in ponds and lakes in their natural habitat. Putting them in a too small container would be like forcing you to live in a small room or closet. You could survive but you'd not be very happy or healthy.
Yes an RES will live in the same environment no matter what country they live in... as I said, they are aquatic turtles. They are NOT native to Malaysia therefore you have to mimic their natural environment. It would be like our taking an animal from your country and forcing it to adapt to the cold weather. It is good to take them outside for natural sunlight. Since you live in a warm country you can do that, those of us that live in a climate that changes with the seasons must find a way to give sunlight by artifical means.. which would be the UVB light.
Also, RES need to eat in water. They do not have saliva and their tongue does not move like most animals. If they aren't in enough water, they won't be able to eat.. and well if they don't eat, they starve and die
The lack of any or all of these things could have been what contributed to your turtles shell problem..

I hope this makes sense to you and that we've been some help
