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54. Get out of my territory! (Scorpion Leaffish and Damsel in a fight)


The temper and the toughness of Damsels are revealed in this clip which provides a fascinating glimpse into the complex behaviours and strategies that fish use to survive and reproduce in their environments.

Damsels are known for their aggressive defence of their territory against any other fish that intrudes into their claimed part of the reef. Often they defend a patch of algae. As semi-herbivores (feeding mainly on algae but also consuming tiny crustaceans and plankton), their allotment provides them with a secure and steady supply of fresh algae that is worth defending against bigger grazers that can decimate their little garden in a split-second.

In this video clip, we see a Threespot Dascyllus (Dascyllus trimaculatus) fending off a Scorpion Leaffish (Taenianotus triacanthus). The Scorpaenoid is a carnivore and thus does not eat algae. Perhaps the damsel is just defending its turf against any fish, herbivore or not? When filming this incredible fish behaviour, I suspected the damsel was guarding its eggs rather than its little garden.

At first sight it was impossible to determine of this little fish with its strong will, possessed an allotment of algae. Also, a cluster of eggs could not be spotted on the ridge of the TUG II, the little wreck both fish call home. While it may be impossible to see the eggs in the video, it is possible that the eggs are located in a crevice or cavity within this artificial reef. However, logical thinking suggests that the Threespot Dascyllus is indeed defending its eggs from a scorpaenoid known for eating eggs. Many fish species, including damsels, lay their eggs in a nest or on a substrate, and then safeguard them from predators until they hatch.

Although the Scorpion Leaffish is armed with venomous spines that could easily and severely hurt or even kill the brave Threespot Dascyllus, the attacker seems to be fended off with ease by the Threespot Dascyllus hitting the scorpaenoid hard with its tail fin to chase it out of its territory.

The behaviour displayed by the Threespot Dascyllus in this video, actively chasing away a potential predator, is consistent with this type of parental care.


Keep the Camera Rolling...you never know what's coming next, or do you? Way too often, a recording is cut short for no obvious reason. Is it the urge of that little finger to press a button? On several occasions, I personally regretted having pressed that button way too early for no apparent reason. Don’t worry about recording too much data on your SD-card, as most cameras come with pre-editing software where you can select the parts of your footage that need to be transferred onto your computer's hard drive.

If you do not possess this kind of software, then it is easy to cut out unwanted footage during the editing process itself. Make sure that you have saved all your recordings on two different hard drives after each dive. Why two? Well, sometimes they crash, and with no extra backup, you risk losing all your footage. Also, make sure you format your SD-card before a day of diving and filming so that you do not run out of storage space on a dive. It is important to follow your camera’s manufacturer’s guidelines when formatting an SD-card!

Puff and slap sounds were added to make the clip complete. The whistling falling sound at the end was added to bring a smile to the spectators' faces. Always end with a good note.

Filming location:

This short underwater videoclip has been filmed in Mauritius 🇲🇺

More on this topic:

For a more in-depth description about the Scorpion Leaffish please go to our vlog post 125 or click on this link: https://www.beyondscuba.com/post/the-scorpion-leaffish-taenianotus-triacanthus

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