SearchResearch Challenge (09/10/19): What's the relationship between these two fish?

I'm scuba diving again ... 

... I know--not a big surprise.  But this time I'm diving with friends on a tropical island, taking a few underwater photos and finding remarkable things that require a bit of research when I get topside.  

In today's Challenge, I'm diving somewhere in the tropics, and today I saw these two fish.  

What's odd, though, is that these fish seem to have some kind of strange relationship that I can't quite figure out.  

Can you? 

(This is a fun fishy SearchResearch Challenge.  It will test your query formation skills and your ability to combine two ideas and find their relationship.)  


1.  Here's Fish #1.  They hang out in rocky crevices, alway near a kind of purple glaze on part of the rocks.  What kind of fish is this??   (For reference, it's about 4 inches long.)  

This is a bit of an unusual shot.  Normally there would be hundreds of these fish swimming all around.  

However, whenever I'd see a fish like this, there would ALWAYS be fish like this nearby: 

(You see several examples of Fish1 in the backwater.  Fish 2 are the larger ones in the top of the photo.) 

So... 

2.  What kind of fish is Fish 2?  (It's about 7 - 8 inches in length.)  

... and the REAL question... what is the relationship between Fish 1 and Fish 2?  

Usually Fish 1 chases Fish 2 out of the crevices, but every so often Fish 2 would zoom into the crevices for a few seconds before darting out again.  


3.  What's going on when Fish 2 quickly swim into the crevices with purple glaze?  



4.  Where is Dan now?? 


Can you answer these questions?  


Be sure to let us know HOW you find the answer to the Challenge.  

Search on!