For a fish that is only an inch long, the critically endangered Devils Hole pupfish certainly has a lot of things to overcome, the least of which is it's tiny size.

First, it lives only in one cave in Death Valley, long known as one of the hottest places on earth. The water there is 92 degrees! It faces varying water levels that impact its ability to spawn, drunk visitors stepped on their eggs, and at one time even started a war between local ranchers and environmentalists that required a ruling by the Supreme Court to decide their fate!

But despite all the adversity, the pupfish are doing remarkably well for being one of the world's most endangered animals. From a low of just 35 fish in 2013, the NPS this year recorded as some 191 fish in total — the most observed in 25 years. 

Biologists noted the fish appeared active and in “remarkable condition,” with “a large number” of young and several individuals observed spawning and courting. They believe the comeback could mean significant changes are in store for their tiny ecosystem, and plan to continue maintaining long-term data to determine how conditions have become more ideal, if at all, and how other variables may have had an impact on their population.