A post on the war prizes the IJN gained from the Russian defeat at Port Arthur, Chemulpo Bay and Tsushima seems in order. No need to go into details, but here are the important ships taken into the Japanese fleet after 1905:
Battleships:
1. Coast defense battleships at Port Arthur -
Imperator Nicolai I (in service 1893) - Japanese name Iki.
General-Admiral Apraxin (1898) - Okinoshima.
Admiral Senyavin (1895) - Minoshima.
2. Sea-going battleships -
Poltava (1898) - Tango.
Peresviet (1901) - Sagami.
Pobieda (1902) - Suwo.
Retvizan (1902) - Hizen.
Orel (1904) - Iwami.
Cruisers:
Bayan, armored cruiser (1902) - Aso.
Varyag, protected cruiser (1900) - Soya.
Novik, protected cruiser (1902) - Sutsuya.
Pallada, scout cruiser (1902) - Tsugaru.
Notes:
-- Other than two 400 ton torpedo gunboats, it does not appear that any destroyers or other craft were taken into the IJN.
-- Most of these ships were used for a time as training ships, except for the battleships Hizen and Iwami. They both served as parts of Japanese battle divisions through the beginning of WW I.
-- It is interesting that the Japanese considered the battleship Hizen and the cruiser Soya the best of the prizes. Both of these ships were built in Philadelphia at William Cramp & Sons at a time when all Russian shipyards were at full capacity at the turn of the 20th century.
-- The other ships mostly were used as guard ships or for administrative duties such as receiving ships, etc.