Hi, how can I get to gold fish market (tung chung st) coming from BP international hotel tsim sha tsui if I take a train?

I think you may mean the Gold Fish Market at 210 Tung Choi Street, 210 Tung Choi St, right?
If so, it is suggested to take a taxi to reach there directly and there is about 2.6km between the two places.
If you want to take the train, you can walk to reach Jordan Station from your hotel to take Tsuen Wan Line to reach Mong Kok Station. Get out of the station from Exit B3, you can ask the local people to find that market easily.