Fishman Karate is a martial art that is practiced by certain skilled members of the fishmen race; it is noted that humans can also learn the fighting style, as Koala apparently is able to use it despite being human. While deadly enough on land, Fishman Karate has a number of devastating underwater moves designed to be suitable with the Fishmen strength and speed along with the mobility that goes while under water and, in some cases, a fishman's personal adaptation (fins, teeth, etc.).
According to Jimbei, the secret of Fishman Karate is mastery of the water in the user's direct vicinity, using its power to send powerful waves impacting the water within the opponent's body. Since every living creature is nothing more than a mass of water, the users of Fishman Karate are able to battle opponents that are usually highly resistant (if not immune) against blows and punches. This was demonstrated against Monkey D. Luffy, a rubber man, who is nearly immune to blunt attacks.
Jimbei also displayed that Fishman Karate can be used effectively on land as he can utilize the water in the atmosphere and make use of it to attack.
This martial art can be learned on Fishman Island, more specifically at the Fishman Karate Dojo. Fishman Karate can also be taught to humans.
Hody Jones has shown extreme power with his Fishman Karate, so much that Usopp claimed that he was above Arlong; this mighty strength has further been boosted by Hody's overdose on the Energy Steroid drugs. However, Jinbe regarded Hody as a novice compared to himself. Despite Hody's power, his Fishman Karate is shown to be at an amateur level in comparison to Jimbei's as he was unable to do any damage to Luffy causing the rubber man to even comment that Hody's level was inferior to Jimbei's. Additionally much of Hody's power was a result of his use of Energy Steroids. He could no longer use these moves as he overdosed on Energy Steroids, which eventually stripped him of all of his natural prowess, rendering him a frail and weak old man, and the fact that he was arrested and put in the prison of the Ryugu Palace.
She is skilled enough at Fishman Karate to be able to teach it and was able to defeat an opponent much larger than her. Not being a fishwoman and still being able to learn the art makes her more impressive. She is shown to be proficient enough to defeat a group of five armed men with only a single strike each.
- This fighting style seems to go by a ranking system not unlike that of standard karate that measures a practitioner's level of expertise in relation to the rank they achieved.