Pufferfish are built to be loners. Most of the ~190 species in family Tetraodontidae are solitary and territorial, which is exactly why a coordinated school of them is one of the stranger sights in reef ecology. The rarity isn’t an accident. Schooling is a hydrodynamic strategy that favors streamlined, fast bodies: • Most schooling fish use body-caudal fin (BCF) propulsion, generating thrust by undulating the trunk and tail • Pufferfish abandoned that. A rigid, boxy body and reduced pelvic skeleton force them into median and paired-fin (MPF) swimming, sculling with pectoral and dorsal fins • The payoff is exquisite low-speed maneuverability but poor top speed, making the tight, polarized geometry of a true school biomechanically awkward So why bother? Defense logic usually makes schooling redundant for them. A puffer’s primary protection is tetrodotoxin, a voltage-gated sodium-channel blocker roughly 1,200 times more toxic than cyanide by mass, sequestered from dietary bacteria r...