Date: February 24th, 8:00am
Today's fish of the day is the sand roller!
The sand roller, scientific name Percopsis transmontana, is a poorly understood freshwater fish in the Pacific Northwest. This fish is separate but related to the well known and widespread troutperch (Percopsis omiscomaycus) or sand minnow.commonly found in the Eastern United States. Little known thus far about the sand roller, due to their cryptic daytime behavior, and limited range. The sand roller has a geographic range including only the Columbia river and its tributaries, found in Idaho, Southern Washington, and Northern Oregon, mostly in the Columbia Basin, lower Snake River, and the mouth of the Columbia near and in the Willamette River. This fish prefers slow moving waters, and sandy bottomed streams with rich vegetation. It is believed they spend their days in deep waters, moving to shallow water in the night to hunt. These fish are light adverse, spending their time hiding under rock structures, possibly leading to the large lack of current information on this species.
Sand rollers throughout their life can get to a total size of around 4 inches, but most will only ever reach a size close to 2-3 inches. These fish can be translucent, green-blue, or various mottled browns, depending on their surroundings. Due to their light aversion, these fish primarily hunt at night. Juveniles tend to eat exclusively zooplankton, but once these fish reach 40mm they transition into eating invertebrates, such as crustaceans, and various flies and fly larvae. These fish swim incredibly strangely, swimming parallel to rock structure either horizontal, vertical, and even upside down along them. Specimens caught in the winter and colder months have been found with nothing in their gut, implying they may be able to survive weeks or even months without food.
Males are distinct from females by a black band found around fins, along with being smaller in size than female sand rollers. Their breeding season is in the Mid spring, around April or when the water reaches close to 60 degrees Fahrenheit, during which males black bands grow larger, and both male and female fish create territories under rocks. These territories are then harshly defended against any and all intruders, often leading to infighting among sand rollers settled close to another. Eggs, once laid on the gravel, are extremely sticky, hatching within a few weeks. Juvenile fish tend to spend their time in weed bays or still waterways off of main rivers. Whereas older fish hide under rocks. These fish become sexually mature around 2-3 years of age, and thought to go through a breeding season each year of life, with the oldest currently caught sand roller being around 6 years in age.
That's the sand roller, everyone! I hope you had a wonderful time learning about them, and I wish you a good day!
Sources:
Katula, R. (1992, April). The northwestern percopsis, the Sand Roller. North American Native Fish Association .https://www.nanfa.org/articles/acpercopsi.shtml
Percopsis transmontana summary page. FishBase. (n.d.-b).https://www.fishbase.se/summary/3066
Sandroller. Oregon Sea Grant. (2024b, August 16).https://seagrant.oregonstate.edu/WRF/native-fishes/sand-roller-family/sandroller