Here's why:
* Mammals are warm-blooded animals that have fur or hair, give birth to live young, and nurse their offspring with milk.
* Amphibians are cold-blooded animals that live in water during their larval stage and on land as adults. They have smooth, moist skin.
* Fish are cold-blooded aquatic vertebrates that breathe through gills and have fins for movement.
Barracudas are clearly fish as they fit the definition of fish perfectly.