Plunging into the World of Freshwater Fishes

A participant demonstrates the “Alligator crawl”

Last Saturday, 8 intrepid explorers joined BRDC staff on a snorkeling program at Straight Branch, a tributary of the South Fork of the Holston. We donned wetsuits to protect us from the 60 degree water and fastened masks and snorkels to plunge into the world of freshwater fishes. While the water in these mountain creeks may seem too shallow for snorkeling (ranging from less than a foot to around 3 feet at the deepest), it is the best way to experience this underwater world. By moving slowly and “alligator crawling” upstream, the fish quickly become accustomed to our presence and swim just inches away from us! Fortunately, we thought to bring an underwater camera this trip to share some of the experience.

A Snubnose Darter tries to blend in with the silt

The aptly named Snubnose Darter (Etheostoma simoterum) stands out from other darters thanks to its very blunt face. While these fish are quite common in our area, they are only found in mid to large side streams in south western Virginia, mostly in tributaries of the Tennessee river system. This male (identified by the row of orange scales above its dark lateral stripe) was curious but cautious, getting close enough to allow everyone to get a good look at him. If his dorsal fins were flared, the striking red would be more visible, but he was likely hiding these colors to help camouflage with the silt below.

The Northern Hog Sucker only swam away when a large group of us got very close

This ~8 inch Northern Hog Sucker (Hypentelium nigricans) was one of the largest fish we got to see, besides a few rainbow and brown trout who sped past us too fast to get a good look. Hog Suckers are mostly benthic feeders, meaning they suck up tiny crustaceans, insects, and algae from the bottoms of stream beds to feed on. They tend to stay close to the stream bed, and only swim quickly when evading predators. With their large size and slow lifestyle, this fish barely minded the gaggle of humans as long as we respected its personal space. 

Large schools of shiners earned their name with shocking colors and mesmerizing iridescence. In this river system, we see several species including Warpaint Shiners (Luxilus coccogenis), named for bold red and black streaks on the males’ faces, Saffron Shiners (Notropis rubricroceus), identified by the males’ gold and scarlet lateral stripes, and Tennessee Shiners (N. leuciodus), who are silver with an olive back and a thin dark lateral stripe. These fish often swim in mixed schools, using bright colors and reflective scales to disorient predators. This defense was certainly effective against our camera- most of our pictures of shiners came out as shiny, unfocused streaks!

Mixed schools of Warpaint Shiners, Saffron Shiners, and Tennessee Shiners were a dazzling sight

Creek Chubs are a common sight, along with their nests if you know what to look for

Creek Chubs (Semotilus atromaculatus) were very abundant today. Almost anywhere we looked, a school of half-foot brown fish lazed along the bottom of the stream. While these fish may look boring compared to some of the flashier fish in this river, they have a fascinating life history. Adults develop large tubercles on their snouts- thick scales that stand out from the face. The males use their tubercles to roll pebbles into nests each spring, providing a place for a courted female to lay her eggs. This streambed was full of these pebble nests, even months after their construction.

Most of the participants were able to catch glimpses of trout, with potential sightings of all three species that occur in southwest Virginia! The beautiful native Brook Trout (Salvelinus fontinalis) can be identified by the squiggly pattern on its back called vermiculation. This river is stocked with Brook trout and Rainbow Trout (Oncorhynchus mykiss), who have small speckles and a pink lateral stripe. Brown Trout (Salmo trutta) are stocked in connecting rivers, and populations have found their way here as well. All three species are very fast swimmers and voracious predators, so they were very difficult to observe except for quick glimpses as they sped past. We managed to photograph one juvenile trout (possibly a young rainbow), seen below.

A juvenile trout, likely Rainbow finally caught on camera! We also saw Brown Trout and everyone’s favorite- Brook Trout. How many other fish can you count in the background?

The barrier between aquatic ecosystems and terrestrial is the thinnest line possible, yet these two environments are completely alien to one another. It’s easy to forget all the action and excitement going on just on the other side of the water’s surface. Snorkeling is an amazing opportunity to literally immerse yourself in a different world. It’s a great reminder that sometimes, the best experiences come when we take a moment to observe and appreciate everything that’s already around us.