I agree that many animals retain a negative reputation based on human misunderstanding/intervention; however, there is always cause and effect at play. IME, what you witnessed was two predators both excited by the presence of food, thus both mindsets turned towards "feeding mode." Most of the time fish react one way or another, either offensively or defensively during feeding. Seemingly, the apparent danger from the eel did not dissuade the puffer from its set objective: feed. This can be seen in many lfs
' as well where porcupine puffers (Diodon holocanthus) often share the same quarters with a variety of eels and during feedings their body's are horribly lacerated (sometimes with insides hanging outside), yet the puffers act no differently other than the need for food. Their ability to "inflate" is a defensive (not offensive) deterrent, but also a major stress factor on their body.
Not trying to downplay your experience and good to see your pufferfish was unharmed, but rather offering personal insight as to why