In Mexico City he would stay at the guest house of wrestlers José Luis Mendieta and Jesus Reza, known as Rambo and Mano Negra respectively, as he started to work for EMLL full-time. He made his debut on the same night that El Solitario unmasked Ángel Blanco, working in front of a much larger crowd than he had in Juárez. Fishman's more brutal wrestling style, common in Juárez but not so in Mexico City, almost immediately made him a rudo (wrestlers who portray the "bad guys") with the fans. During his early days he won a couple of low ranking masks, defeating El Médico I, El Monarca and Professor Konak in Luchas de Apuestas, or bet matches, as a way to establish him as a rising star in EMLL. Further promotional support came on October 3, 1973 where EMLL decided he should win the Mexican National Welterweight Championship defeating El Marquez for the championship. On December 5, 1974 he unmasked a wrestler known as the Durango Kid after beating him in a Luchas de Apuestas match. His run as the Mexican National Welterweight Champion lasted over two-and-a-half year before it was vacated on March 5, 1975. Months later Fishman regained the title by defeating Alberto Muñoz in the finals of a tournament to regain the Welterweight Championship. On February 4, 1976 Fishman challenged Ringo Mendoza for the Mexican National Middleweight Championship but was not able to win it, this was rare for the time, both because of the fact that Fishman was already a champion and that he was clearly identified as a welterweight. On April 23, 1976, in the main event of the 20. Aniversario de Arena México show, Fishman defeated El Faraón in a Luchas de Apuestas match, forcing Faraón to unmask and reveal his real name after the match as per lucha libre traditions. The Apuestas success was followed up by on April 9 when he defeated Blue Demon to win the NWA World Welterweight Championship, one of the top ranked championships in EMLL. With this win he vacated the Mexican National Welterweight Championship to allow him to focus on the NWA World title. On November 19, 1976 Fishman lost the title to Mano Negra as a part of a long running storyline between the two that had begun over the summer. In early 1977 he defeated Blue Demon to become a three time Mexican National Welterweight Champion. At this time he became involved in a three-way storyline against two other hated rudo characters El Cobarde and Sangre Chicana. The three-way storyline was the driving force behind both the first 44th Anniversary Show and the second 44th Anniversary Shows held in September 1977. On the first show, on September 23, the three men competed in a three-way Luchas de Apuestas match, in which El Cobarde was able to pin Fishman to escape from the match with his mask. In the end Fishman pinned Sangre Chicana, forcing him to unmask at the end of the show. The following week El Cobarde caused Fishman to lose the Mexican National Weltweight Championship to Kung Fu, leading to the two facing off for their masks the following day. On September 27 Fishman defeated his longtime back stage friend El Cobarde, forcing him to unmask, giving Fishman two major mask wins within a week of each other.