stricks760 wrote:

Gnats, everywhere, swarming in little clusters. They don't bite or
anything, and generally mind their own business.

Does this indicate any problem? If I want them to become deceased, is there
a safe way to do it around the pond?

Try getting some yellow plastic and smear some motor oil on it with a
rag (the spontaneous combustion problem involves veg oil, not mineral
oils, so don't worry about burning the place down). Hang the plastic
near the pond as an experiment.

This is the sort of thing I'm thinking of:

http://www.marchbiological.com/L/misc.html

Sticky Yellow Cards

Target pests: Whitefly, aphids, fruitfly, gnats & wasps

The name says it all. They are cards, colored yellow with a sticky
coating. Pests from aphids to wasps are attracted to the yellow color
and get stuck and die. The best part is Beneficial Insects are not
attracted to yellow so they will work together well. Lasts until
completely covered. Use one or two in a greenhouse or garden to
monitor if there is a pest problem or place every 10 to 15 feet
depending on the level of infestation. 5 card per pack with hanging wire.

Pack of 5 $3.25

The rest of the page is interesting as well.