Koichi Tanaka has 11 losses against 11 opponents on his MMA record. For a list of Tanaka's best fights, refer to "Best fights of Koichi Tanaka".
On February 4, 2007 Koichi Tanaka faced off against Yuichi Miyagi in a lightweight bout at age 35. He was coming in with a record of 2-11-1 (2). Tanaka lost the fight via 2-round unanimous decision.
On October 1, 2006 Koichi Tanaka faced off against Kenji Takeshige in a lightweight bout at age 34. He was coming in with a record of 2-10-1 (2). Tanaka lost the fight via 2nd-round submission.
On September 23, 2001 Koichi Tanaka faced off against Hiroshi Komatsu in a bantamweight bout at age 29. He was coming in with a record of 2-9-1 (2). Tanaka lost the fight via 2-round unanimous decision.
On August 15, 2001 Koichi Tanaka faced off against Akitoshi Tamura in a featherweight bout at age 29. He was coming in with a record of 2-8-1 (2), and Tamura was 21 years old and with a record of 0-1 (0). Tanaka lost the fight via 2-round unanimous decision.
On June 14, 2001 Koichi Tanaka faced off against Makoto Ishikawa in a featherweight bout at age 29. He was coming in with a record of 2-7-1 (2), and Ishikawa was 26 years old and with a record of 4-3 (1). Tanaka lost the fight via 2-round unanimous decision.
On February 18, 2001 Koichi Tanaka faced off against Yoshihiro Fujita in a bantamweight bout at age 29. He was coming in with a record of 2-6-1 (2), and Fujita was 31 years old and with a record of 0-3-1 (0). Tanaka lost the fight via 1st-round choke-out.
On October 29, 1999 Koichi Tanaka faced off against Chikara Miyake in a featherweight bout at age 28. He was coming in with a record of 2-5-1 (2). Tanaka lost the fight via 1st-round submission.
On August 4, 1999 Koichi Tanaka faced off against Yohei Nanbu in a featherweight bout at age 27. He was coming in with a record of 2-4-1 (2), and Nanbu was 22 years old and with a record of 0-1-1 (0). Tanaka lost the fight via 2-round majority decision.
On May 27, 1999 Koichi Tanaka faced off against Isao Tanimura in a welterweight bout at age 27. He was coming in with a record of 2-3-1 (2). Tanaka lost the fight via 2-round majority decision.
On September 18, 1998 Koichi Tanaka faced off against Jutaro Nakao in a lightweight bout at age 26. He was coming in with a record of 1-2-1 (1), and Nakao was 27 years old and with a record of 5-3-1 (5). Tanaka lost the fight via 1st-round submission.
On January 17, 1998 Koichi Tanaka faced off against Tetsuji Kato at age 26. He was coming in with a record of 1-1 (1). Tanaka lost the fight via 1st-round choke-out.