Date: January 8th 2026, 12:30pm
Happy Thursday, everybody! Today's fish of the day is the Lahontan redside shiner!
The Lahontan redside shiner, also known as the redside minnow, or scientific name Richardsonius egregius, is a lesser known shiner of the West. Found in and around the interior basin of Western America stretching from South Eastern Oregon, down Eastern California and throughout Nevada. This fish once was spread through the, now dried, lake Lahontan which existed in the Pleistocene 10 million years ago. In the modern day this lake has split into various streams, lakes, and reservoirs, most of which the redside shiner thrives in. Often mistaken for the Lahontan redside shiners better known relative, the Columbia redside shiner, which shares the northern section of the Lahontan's range. These fish, despite sharing very similar bodies and coloring, can be told apart by the Lahontan shiner lacking some of the dorsal and anal rays, as well as a longer snout and thinner body.
These fish live in slow pools, quiet streams, and lake margins where these fish can surface and catch drifting insects. Insects, larvae, and various crustaceans make up the diet in near entirety, with algae and other vegetation making up the remainder. This diet supports these fish to get up to 17cm maximum, although most fish will only get around 7cm, with no major difference between the sexes of fish. The behavior of the Lahontan redside shiner is social, and these fish often school together for hunting, breeding, and other schooling behaviors.
Breeding season for these fishes happens between May-August with a high in June. This breeding season is influenced not by temperature but by the light level, with aquarists struggling to breed the shiners, as they require a slow increase of light over the year, only breeding once the sun is out for enough hours and the water is warm. This may be due to these fish spending winter submerged in deeper pools where they remain near motionless for months. During breeding season in the wild, these Lahontan redside shiners gather in groups of 20-100 fish, swarming in shallow water above gravel or sand laying eggs on the bottom. These eggs will remain stuck to these rocks from the adhesive in their coating until they hatch in a few weeks. After this, these fish will mature within a year and survive for up to 5!
That's the Lahontan redside shiner everybody! I hope you enjoyed reading about them.
sources:
Lahontan Redside (richardsonius egregius) - species profile. USGS Nonindigenous Aquatic Species Database. (n.d.). https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=647
Richardsonius Egregius summary page. (n.d.-c). https://www.fishbase.se/summary/Richardsonius-egregius
NANFA captive care: Redside Shiners (richardsonius). https://www.nanfa.org/captivecare/richardsonius.shtml