Couple of Answers Needed

[whatcaneyedo]

Yes the quick and to the point answers are always nice. I like books though.

1. Currents come to a lull between tides and sometimes the wind doesn't blow. Some fish hunt and graze others like stone fish just sit and wait for their food to come to them.
2. Some fish can see well enough at night with the small amount of light given, others might have a strong sense of smell to guide them to their prey. Mass spawning events in time with lunar cycles have been well documented and caught on video (would you like to borrow some of my documentary videos?). Have you never noticed your fish sleeping? Some of mine are quite obvious about it while others seem to be active 24/7. Some fish can shut off half of their brain at a time to allow it some rest while still allowing them to swim about.
3. The sun warms water at the surface but cold water always rises from deep below (ice floats) and mixes in. Ideal water temperature depends on the species in question but 26 celsius or 78 fahrenheit is pretty popular for a typical reef tank because its somewhere in between the acceptable extremes. Dr Ron Shimek actually states that 83 fahrenheit is the ideal temperature for most coral in his book on marine inverts...
4. The ocean is fast and can dilute a lot of natural pollution. Healthy reefs are typically very nutrient poor however because one fish's waste is another coral's or algae's meal. So while skimming does occur naturally its plays a lesser role in nature than it does within our tiny over stocked closed systems. Foam that washes up on beaches surrounding developed areas is bound to have a lot sewage and industrial/agricultural run off in it. FYI according to Marvel Comics playing in sewage gives you super powers so play away.

I'm not quoting anything here, this is just what I've retained. I'm sure others will have better answers.