Big fish in a little pond and the pond is shrinking from lack of rain over the last two weeks. Some Chinese tallow branches hanging over the pond provide some size perspective. Over the last several years I've never seen such a big fish in this intermittent pond that usually dries up several times each year with no rain for a month or more. I first spotted it here: http://www.inaturalist.org/observations/4067703
"A ""butterfly"" carp, analogous to the butterfly koi. What are the growths on its nares? The barbels were also branched and feather-like. Other ""butterfly"" carp in this pond have the same features but those at other sites do not."
This organism is found in bodies of water warmer than 20 degrees Celsius, and preferably in slow or even standing water. Carp's role in their ecosystems is to feed on algae and other smaller organisms.