Trumpetfish are demersal, coastal fish (‘demersal’ descibes the zone in the water column immediately above the sea-floor).
They are primarily pescivores (fish-eaters) who spend a lot of their time within groups of other fish. They do this partly for protection – safety in numbers – and partly to exploit foraging opportunities. Sometimes unsuspecting divers even occasionally provide cover for sneaky Trumpetfish: something which can offer up quite a surprise if you aren’t expecting to see one just over your shoulder!
It is common to see Trumpetfish hanging in a vertical, head-down position. This is preparation for hunting small benthic (bottom-dwelling) species. Their long snout and small mouth opening allow them to create tremendous suction (like a drinking-straw) to hoover up small prey from the sea-floor. They also often shadow other, larger foraging fish such as parrot fish, whilst they gaze on algae. This feeding will disturb small fish and mobile invertebrates (like shrimp) who then become easy prey for the Trumpetfish.
Another feeding technique is to shadow other specie, such as turtles, who aren’t seen to be a threat to many small fish. This allows the Trumpetfish to get within a metre or so of their prey, at which point they can make a rapid final lunge at their unsuspecting prey, who they will swallow whole!
Along their back there is a ridge of spines, which usually lay flat and hidden, but can be extended for protection. Below their mouth is also a small sensory barbel. It is not known for sure exactly the purpose of this, but it is believed that it helps them to detect nearby prey.
They have an elaborate courtship display, which utilises their colour-changing abilities to stunning effect. When reproducing, the male Trumpetfish carry the fertilised eggs until they are ready to hatch.
Next time you see one on a dive, we encourage you to watch it for a few minutes. Don’t just ‘see’ it, but really watch it. You will be very likely to see some of the behaviours described here: especially their impressive colour changing, which they do very frequently.
We hope you enjoy the moment all the more for knowing a little bit more about what you are seeing.