For the dimensionally impaired among you, the OP’s most recently stated dimensions of 1000 x 500 x 310 is approximately equivalent to 40” x 20” x 12”, which is approximately 40 US gallons.
This may not be a monster tank, but is a perfectly reasonably sized aquarium for many smaller community fish (e.g., tetras, guppies, dwarf gouramies, betta).
To the OP: given that you’re a novice, I would advise sticking with freshwater fish. While a SW clown fish could technically fit in there, you would need a lot more space for accessory filtration equipment (sump, skimmer etc.), which it doesn’t sound like you have room for.