- Shredder - Montes was freed from prison by Shredder after he was caught burglarizing Shredder's property by the police, mainly because he found his burglarizing skills very useful to his clan, as well as the fact that Montes likes having a job where he gets to crack skulls almost everyday. Montes is probably thankful for Shredder's action and for his own freedom. But like everyone else, he is afriad of him so he tries to stick up to him, but it mostly fails.
- Chris Bradford / Dogpound / Rahzar - Even though Shredder put them together as a pair, Montes didn't cooperate with Bradford well. They frequently berated each other and quarreled amongst themselves, and their different fighting styles and attitudes have been shown to clash. However, they were driven by the common goal set by Shredder to defeat the Turtles, so they were able to put their squabbles aside and fight together whenever the situation calls.
- Baxter Stockman / Stockman-Fly - Fishface viewed Stockman as an ally at first, because he was capable made a pair of robotic legs and a water-breathing rig for Fishface, but when he and Dogpound harassed him when Stockman wouldn't follow their orders, he betrayed them by trapping them with the Turtles in his Maze of Doom. Even though he escaped after his defeat, Fishface crossed paths with Stockman again and asked him to help him and Rahzar to become human again, outfitting him with a mutagen collar to ensure that Stockman kept his promise.
- Tiger Claw - Fishface showed clear signs of fear towards Tiger Claw, either due to an instance in the past, or because of their respective mutations (as a tigers diet can include fish), as he uncharacteristically shows hospitality to Tiger Claw.
- Anton Zeck / Bebop - Fishface fought Zeck at the docks during the deal with Shredder and captures him with such a success. Afterwards, Fishface pushes him into a mutagen vat filled with warthog DNA, causing Zeck's mutation.
- Raphael- Montes shares several similarities with Raph, such as what they do because they both like a job where they get to "crack skulls every day". The two also have a rivalry, and duel whenever they meet. Raph is also the only turtle who has near equal skills to Fishface. In Baxter's Gambit, the two of them were forced to work together and split away from the other Turtles and Dogpound. Raph saves Fishface from a laser saw, and Fishface saves him from a deadly fan. The two show great teamwork and destroy Sockman's UFO. He even tells Raph why he's in the Foot Clan.
- Leonardo- Fishface and Leo don't really interact often, but when trapped in the Maze of Doom, they come to positive terms when deciding who will go first through the doorway.
- Michelangelo- Fishface and Mikey don't interact much, but when the turtle robbed him of his errand boy (Mondo Gecko) after their race, Fishface's hatred for him increases. Also he hates the name Mikey gave him and calls it an insult.
Splinter- Montes (along with Bradford) was assigned to hunt down and find Splinter for Shredder throughout the series. Due to this, Fishface has come to despise Splinter and his disciples, the Turtles.
Karai- During their time as allies, Montes and Karai interacted very little, but it can be presumed by their little interaction seen that Montes has a rather indifferent disregard for her, even when feeding her prison food when she was locked in the dungeons.
Mondo Gecko- Fishface took Mondo as his errand boy, but after being slapped away by his own boss, Mondo realized Fishface's true nature and turned against him.