I've been busy...
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| Spanish hogfish (in front), followed closely by a Trumpetfish. Why? |
...not just with work, but with another dive vacation.
And the vacation causes me to be curious about all kinds of things. In this case, there's a peculiar behavior that I've seen multiple times. Two fish of different species will often swim in perfect formation, like two fighter pilots flying in tight formation through the reef. Here's what it looks like in motion:
I've seen this happen with many different species in different oceans and have always wondered:
1. What is this kind of behavior called?
2. Why do they do this?
3. In the pic above, we have a hogfish being closely followed by a trumpetfish. What other combinations of fish species might I find doing this?
Can you help out this scuba diver figure out what's going on with this strange fishy behavior?
Let us know in the comments. Be sure to say HOW you figured it out (note that every method is acceptable, including AI--just tell us how you used the AI.)
Keep Searching!
Apparently, it's called "shadowing", and can serve as camouflage, or for energy-saving gliding.
ReplyDeleteThis seemed to be the kind of question I would ask a good AI. So that's exactly what I did. I shared the blog post link and just asked "Two fish off different species gliding in formation. Why?"
Here's Gemini 3.1 Pro answer:
https://g.co/gemini/share/59d56ce190df
The next step would be checking if the answer's valid and accurate. And trying to find examples of pairs of species commonly found with this behaviour.
Interesting. If you asked the question ALONE (i.e., without the link to my blog post), you don't get the complete answer. IF you include the link to the post (as you did), then you get the right answer, "shadowing" or "shadow hunting." Nice job.
DeleteI went to Gemini and asked "How would you respond on Dr. Russell's questions in this blog post? Make sure you analyze his image included in the post of the Spanish hogfish (in front), followed closely by a Trumpetfish. https://searchresearch1.blogspot.com/2026/05/searchresearch-562026-what-is-this.html"
ReplyDeleteThen I asked it to evaluate the answers using Dr. Russell's techniques. I received full stop replies about that being against guidelines. Tried rewording it several different ways. Always against guidelines. Finally removing mention of Dr. Russell's techniques and shortening to "Evaluate your answers above" provided an analysis, although one might question the example of search operator as removing -sports in a search did not give any sports references on the SERP (Search Engine Results Page).
Here is my conversation. View the Gemini Conversation - What is this called and why do they do that?
Also nice... very much the same approach as Luis Miguel. Well done.
DeleteChatGPT (GPT-5.5) [Improve this prompt: Act as a multidisciplinary team of experts in diving, oceanography, reef fish behavior, and related topics. I've been diving and have noticed a peculiar behavior that I've observed several times. Two fish of different species often swim in perfect formation, like two fighter pilots flying in close formation across the reef. For example, a hogfish closely followed by a trumpetfish. 1. What is this type of behavior called? 2. Why do they do this? Use only reliable sources. 3. What other combinations of fish species might I find doing this? Keep your answers short, concise, and accurate.]. Once the prompt was improved, I ran it and iterated.
ReplyDelete1. The phenomenon is generally known as interspecific foraging association. In the specific case of the trumpetfish (Aulostomus maculatus), the behavior is often described as shadowing and, in some studies, as a form of behavioral aggressive mimicry. 2. Primarily to improve hunting. The trumpetfish swims extremely close to non-threatening fish—such as parrotfish, surgeonfish, or hogfish—to conceal its predatory silhouette and approach its prey without alarming them. Experimental studies on Caribbean reefs showed that prey fish, such as damselfish, are less likely to detect the trumpetfish when it swims close to another species. The benefit appears to accrue almost entirely to the trumpetfish; the "escort fish" often doesn't gain a clear advantage. 3. Trumpetfish + parrotfish (Sparisoma spp.) The trumpetfish uses the parrotfish as visual cover while hunting. Trumpetfish + surgeonfish (Acanthurus spp.) It hides inside or next to herbivorous fish that don't raise alarm. Trumpetfish + hogfish (Lachnolaimus maximus). Frequently observed on Caribbean reefs; probably the same concealment strategy. Juvenile jacks + sharks or large rays. They use larger animals for protection and mobile camouflage. Sea bass + sharks/turtles. Association for transportation, protection, and feeding, though not for stealth hunting.
Well done!
DeleteAI for me - and as I no longer trust answers without verification on AI, I have spend time researching what the AI tells me or try the same prompt with different AI chatbots and look to see the common elements - which is what I did here. (I'm lazy - it's faster this way than to google each element and check them - or even read the detailed sources given).
ReplyDeleteSame prompt - basically from your question (so I didn't say why I wanted to know or who I was or other prompt elements I normally use - but I think in this case could bias the answer).
There's a peculiar behavior for fish. Two fish of different species will often swim in perfect formation, like two fighter pilots flying in tight formation through the reef.
This seems to happen with many different species in different oceans.
What is this kind of behavior called?
Why do they do this?
In the attached picture above (your photo), we have a hogfish being closely followed by a trumpetfish. What other combinations of fish species might I find doing this?
Answers are at:
https://claude.ai/share/76a2c980-1f3a-4f16-a857-1099a03b3085
https://chatgpt.com/share/69fb4dff-9674-8386-b6a5-f378fac7db28
https://gemini.google.com/share/9ab42940f088
https://www.perplexity.ai/search/48183a04-cfce-4590-a012-c0d0e657f92b
I then pasted the 4 responses into NoteBookLM (as it couldn't apparently read the above links - and nor could chatgpt when I asked it to summarise common elements from 3 out of 4 answers or all 4). So I pasted into NotebookLM and asked: "Please can you summarise these 4 chat responses, pulling out the common elements. Anything that appears in only one of these, discount / ignore. I want the elements that are in 3 out of the 4 or all the following responses. If there is nothing common at all, please tell me."
The answers I got are in my next comment. (I said I'm lazy.... so I SHOULD check all this - and if this was for work, I would but it looks OK so I'll go with it, which in work could be fatal but in this sort of exercise.... laziness wins. And "scouts honour" I won't tell it to the judge in a court case).
Based on the four sources provided, the following elements are consistent across at least three (and in most cases, all four) of the accounts:
ReplyDeleteCommon Terminology
The sources share a standard vocabulary for describing these interactions:
Shadowing: This is the most common term used to describe the behavior of one fish following another closely
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Following behavior: This is used as a general descriptor for species that trail others to gain an ecological advantage
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Shadow hunting or stalking: This specific term is used when describing the predatory intent of the follower
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Common Motivations
The sources agree on three primary reasons why fish form these associations:
Hunting Camouflage and Stealth: This is the primary driver for trumpetfish. By staying close to a "harmless" fish, the predator disguises its silhouette from prey, allowing it to strike from a point-blank range
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Feeding Opportunism: Many species follow bottom-feeders to capitalize on food (such as invertebrates) that is stirred up or flushed out of the sand by the lead fish
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Protection from Predators: A follower may gain safety by staying near a larger or more vigilant species, which can cause potential predators to overlook them or hesitate to attack
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Common Species Pairings
Specific combinations of fish are repeatedly cited as classic examples of these behaviors:
Trumpetfish and Hogfish: Frequently used as the primary example of a predatory "shadowing" association
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Trumpetfish and Parrotfish: Listed across the sources as one of the most common host-follower pairings for hunting
.
Trumpetfish and Angelfish: Another common example of the trumpetfish using a large reef resident for concealment
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Goatfish and Followers (e.g., Wrasses or Jacks): A standard example of feeding opportunism where followers grab prey flushed from the sand
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Stingrays and Followers (e.g., Jacks): Similar to goatfish, large rays disturb the bottom, creating feeding opportunities for trailing fish
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The "Moving Blind" Concept
At least three sources describe the larger fish as acting like a moving blind, camouflage screen, or "stalking horse"
. This allows the following fish to hide its presence and approach prey that would otherwise recognize its predatory silhouette
And just for the fun of it, I turned the results into a movie - downloaded at https://tinyurl.com/oceanicalliances
ReplyDeleteI really ought to check the truth of all this. It sounds convincing - and makes a fun video that explains what's happening so I hope it's all true.
The video is wonderful! Thanks for generating this.
DeleteAfter reading the answers:
ReplyDelete[fish shadowing}
2023 Shadowing questions answered
https://blog.willyvanstrien.nl/2023/09/01/shadowing-behaviour/
{fish shadowing first observed}
https://theconversation.com/how-some-fish-learned-to-hide-behind-others-to-hunt-new-research-211051
Animals can struggle to balance their need to move with their need to remain concealed and evolution has helped them develop some creative solutions. For example, the wrap-around spider, found in Australia, spins a new web every evening
2023: An experiment on coral reefs provides the first evidence that predators use other animals for motion camouflage to approach their prey without detection.
https://www.cam.ac.uk/research/news/stealth-swimmers-the-fish-that-hide-behind-others-to-hunt
2025: Scientists have revealed for the first time that some fish sneak up on their prey by hiding behind sharks
https://www.eurekalert.org/news-releases/1078607
I tried with Perplexity.
DeleteHere is the link
https://www.perplexity.ai/search/can-you-please-analyze-and-ans-3WqhMZ_dQcm4ma8o2VUQHg#2
At the end...Technical name for the behavior is often called a “follower association” or more specifically a “nuclear‑follower” foraging association in fish behavior studies.
However those names haven't been mentioned in previous answers so I'm thinking it is not correct