Angler Sputtlefish

The Angler Sputtlefish is a fully aquatic enemy found in Pikmin Z. Being a species of Sputtlefish, it holds some similarities, except it's darker-toned and has a third extension off of its head to hold a bulb in front of it to lure prey.

Biology
The Angler Sputtlefish is considered as a relative to the standard Sputtlefish, developing into a type of ambush predator, evolving an extension from its forehead. It will not pursue leaders, but it will try to catch any prey that wanders in its light. This becomes more effective during the night than the day.
 * Diet: small, aquatic animals
 * Predators: large aquatic carnivores, Fishing Phosbat

Piklopedia entry

 * "This species of Sputtlefish has turned from a simple fish to a silent hunter. It can't swim very fast, so it relies on its light to lure prey close, to which it swallows up very quickly. Though, I can see a predator using this light to eat an Angler Sputtlefish as well."

Strategy
During the day, there's little to worry about over the Angler Sputtlefish during the day, but at night it will try to catch prey that enters its field of light. Swarming will quickly do the creature in if it hasn't seen anything, but it's recommended that it be attacked from behind if it does, otherwise it'll consume Pikmin rather quickly.