That's fuel seperation in photos, very nasty stuff and corrosive - water and alcohol has combined and will stay that way.
That's what you look for in the racor clear fuel bowls, dark fuel.
When first using ethanol when regular fuel has been used, the ethanol scrubs the tank clean and the water at the bottom of all gas tanks then gets scavenged by the alcohol, too much and the seperation occurs. The particulates can be filtered - use the larger filters like racors up front first in line. The small ones at the motor are overwelmed.
I use the 2 micron racors with no back pressure issues, but the 10 are recommended by Yamaha.
When converting to ethanol - change out all fuel lines first. The new materials can handle it.
Change out O rings periodically on fuel ports (every 3 yrs) , and regularly wipe clean the o ring groove on both contact sides. Inpsect each time opened for cuts on surface.
During seasonal times of condensation (as found on car or boat in the AM or PM - soaking wet), you are vulnerable to condensation internal tank walls above fuel line. Keep tanks full(er) than empty(ier) duing these seasons in particular, use fuel stabilizer always. I use marine Stabil.
Buy fuel in recommended stations, water can be pumped into your boat from fuel dock and you will not be able to prove it nonetheless have big problem expenses.
It's been some time since ethanol took over in NY downstate area (12 yrs now or so (?)), same problems occurred which included blown motors new ones too, desintegrating fuel lines to a point of ply seperation and collapse internal, turining to goo, clogged up fuel systems on motors, and melting fibergass tanks in Bertrams that resulted in resin coated valve stems that cripped motors to limited RPM.
It has been advised when conveting to ethanol to suck clean any fuel in existing tanks, this can be done via fuel level flange removal and insert tube to bottom rear, be careful doing this, no sparks.
These is a regulatory law in place for some time now for manufacturers to close our fuel systems just like have been in cars since the 70s, with a mandated implementation date, which I can't recall at the moment. When this is done the internal condensation source will be ended.
Tend to use you fuel load in a way that it is periodically refreshed with new fuel vs. hanging around older fuel longer. Which means for me based on my trips I refuel at about 80-90 gallons down use fuel managemnet gauge and run about no more than 80% full (main tank) to economize by avoiding excess weight.
Good luck.