Robotic　fish　can　enhance　swimming　performance　through　bistability,　enabling　rapid　response　and　increased　force.　Existing　bistable　robotic　fish　are　typically　classified　as　either　purely　soft　or　purely　rigid,　which　may　constrain　their　performance.　This　letter　introduces　the　rigid-soft　coupled　tensegrity　robotic　fish.　The　potential　energy　parameters,　such　as　the　energy　barrier,　are　modified　by　adjusting　the　preload　of　the　tension　elements.　An　intermittent　gear　transmission　scheme　is　proposed　to　accommodate　the　bistable　state　snapping.　Experiments　with　the　robotic　fish　were　conducted　to　measure　potential　energy,　swing　speed,　swimming　performance,　and　thrust.　The　experimental　results　showed　that　the　robotic　fish＇s　maximum　swimming　speed,　minimum　cost　of　transport,　and　maximum　thrust　were　1.1　BL/s,　10.5　J/kg/m,　and　8.77　N,　respectively.　These　metrics　rank　above　the　medium　level　compared　to　existing　bistable　robotic　fish.　Adjusting　the　energy　barrier　increases　the　average　angular　velocities　of　the　robotic　fish＇s　step　response　and　continuous　swing　by　88.8　s　and　503,　respectively.　Moreover,　the　maximum　thrust　increased　by　97.2%,　and　the　average　thrust　increased　by　1400%.　These　findings　underscore　the　potential　of　mechanisms　for　adjusting　bistable　characteristics　to　improve　the　swimming　performance　of　robotic　fish,　providing　valuable　insights　for　designing　future　generations　of　robotic　fish.　　©　2025　IEEE.