thebiggerthebetter Ive had the same thing happen SAL vs WAL… in the end my WAL was larger so it “won”, but the SAL was definitely the instigator. They would lip lock like cichlids and actually wore lips down to the bone. Josh/Rich have had lung vs lung trouble also with SAL… there more than fine with other fish but do not like other lungs …
IMO its better in the long run, WAL can cut fish in half and i wouldnt risk the bichir collection with one. My old WAL was a sleeper… he’d cohab fine for years at a time then id find fish mutilated beyond belief lol… For me, “open water” fish were the best tank mates. Even then i had some large 8”+ geo brasilensis get decapitated after many years with the WAL. My lungs seemed to “turn” around the 28-30” mark. WAL and Aethiopicus. Always a craps shoot tho. Many people out there with lungs that dont bother anything. Trial and error as u know well.