I think fishmen (like the chaksa and the antipodes) were exalted by the Tohaa, so they are fluffy here. Looking at Longarms, there’s nothing good about them. The hypothetical base profile (the one with Combi Rifle, that doesn’t exist) would cost 22 pts, for that it shoots worse than a fusilier. The actual weapons you would take cost 27 or 31 pts, for that you get BS11 and a wound. It’s just pure bloat and uselessness.