Could you check and correct this fabel if there are any grammar and lexical mistakes, please?
Poor dog
Once upon a time, there was a dog which whilst passing through a bridge with a bone in its mouth, saw its own face glinting on the water. The dog thought witnessing itself that there was another dog biting a bone. And he decided to deprive the other dog of its bone on a whim. Quickly the dog put its nosh-up onto the ground and plunged into the river in the hope of obtaining extra bone. But unluckily, it could not find the other dog and the wanted bone in the water. On the contrary, the dog wasn’t able to swim upstream against very strong currents to reach the bridge. And hence it drowned in this accident to satisfy its unreasonable caprice. In addition, the dog lost his own bone.
Once upon a time, there was a dog which who, (In fables animals are given human characteristics, so who/his, etc. would be better than which/its, etc. in my opinion.) whilst passing through over a bridge with a bone in its mouth (Did the bridge have a bone in its mouth?), saw his own face glinting on the water. The dog was holding a juicy bone in his mouth at the time and The dog thought upon witnessing itself his reflection in the water, thought that there was another dog biting a bone. There and then, on a whim, he decided to deprive the other dog of his bone. Quickly the dog put its nosh-up (I understand the meaning, and might use this term in story telling, but wouldn’t choose to use it in story writing) onto the ground and plunged into the river in the hope of obtaining an extra bone. Unluckily, it Of course, he could not find the other dog and the desired bone in the water. On the contrary, he had lost his own bone because unluckily for him, he wasn’t able to swim upstream against very strong currents to reach the bridge. Hence he drowned in this accident trying to satisfy his unreasonable caprice. In addition, the dog lost his own bone.
I know a similar fable with a not quite so tragic end. The dog dropped his own bone in the water whilst reaching for the ‘juicier’ bone held by the ‘other’ dog. As he was then unable to retrieve his own bone (and the other dog’s bone didn’t exist) he lost it.