I had one in a 55, 3 in a 75 should be fine since they school. they jump often, and love crickets. try keeping them with wide or tall fish they can't get their mouth around
p.s I wouldn't keep eel like fish with one. mine killed and tried to eat a lesser siren 3 inches longer then himself
p.s I wouldn't keep eel like fish with one. mine killed and tried to eat a lesser siren 3 inches longer then himself