If you are coming to Moscow from St. Petersburg, the chances are you will arrive at Leningrad Station, while Trans-Siberian services arrive at Yaroslavl Station. All three stations are located on Komsomolskaya Ploshchad, which is about 20 km from the Aquarium Hotel.
By taxi
The journey to the hotel by taxi will take about 30 minutes in clear traffic, and taxis should cost $30-40. Alternatively, you can order a transfer with a driver to meet your train here.
By metro
Komsomolskaya Metro Stations is accessible from the concourses of all three stations. Take the red line and travel five stops south to Biblioteka Lenina, and then change to the dark-blue line and travel nine stops west to Maykinino. From there it is a few minutes' walk to the Aquarium Hotel.