SearchResearch (5/6/2026): What is this called and why do they do that?

 I've been busy... 

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!