Summer is the season for being on the water in the Adirondacks, and a canoe or kayak is the perfect way to explore the many ponds, slow-moving rivers and marshes that exist throughout the Park. While these shallow, muddy-bottomed settings may not be great for swimming, the rusty-tan water occasionally covered with patches of floating leaves and strands of submerged vegetation does teem with life. Among the residents of these quiet, weedy waterways is the redbelly dace (Phoxinus eos), a common and widespread member of the minnow family of fish.
The redbelly dace is a small fish, averaging only two and a half inches in length when fully grown at the age of three. Like other minnows, this species has a single dorsal fin supported by flexible elements or rays, rather than sharp-pointed spines and lacks the adipose fin characteristic of the members of the trout and salmon family. As its name implies, this type of dace has a distinctive red color to the lower portion of its sides that expands in size and increases in brightness as the summer breeding season approaches, especially in the males. The redbelly dace also has an olive-silvery back and one very conspicuous black line, along with a few other stripes, that extends from its gill cover to the base of its tail fin.
Much of the ecological success of this minnow is attributed to its preference for a life in waterways that supports few large, predatory fish. Beaver ponds and other similar waterways that contain relatively high concentrations of tannic acid are the locations most likely to fit this category. Because conifers are rich sources of tannic acid, water that originates in softwood forests often contains substantial amounts of this naturally occurring acid.
Along with staining the water a dark, tea color, tannic acid lowers the pH of the environment and creates chemical conditions intolerable to some organisms. Brook trout are able to survive in such bodies of water however, this cold hardy game fish confines its activities to deeper locations and avoids the warm shallows frequented by the redbelly dace. The perch is another fish that is able to function in the discolored waters that flow from boreal woodlands and other stands of evergreens. While this predator does eat some dace, perch prefer more open areas further from shore, not the weed infested places where small schools of redbelly dace congregate.
The merganser and kingfisher are reported to be among this minnows main natural enemies as both of these birds frequently search close to shore for small fish. The loon, like perch, tends to concentrate its fishing efforts in deeper and more open stretches of water which limits its predation on the redbelly dace. Also, this minnow is not as large and as meaty as some other types of fish, like the golden shiner, which minimizes its value to a creature the size of the loon.
Like most types of minnows, the redbelly dace gets its nourishment from the wide array of aquatic organisms that exist around it. Animals that range in size from zooplankton to the larvae of black flies, mayflies and caddisflies are eaten by this dace as it prowls the area for items to ingest. Various types of algae and other small water plants are also consumed, making the dace an omnivore.
As the water warms to near 70 in the shallows during June, dace enter into a prolonged breeding period that lasts for most of the summer. When a female is ready to lay her eggs, she displays certain movements that alert nearby males of her condition. She then quickly swims into an area of submerged weeds or a thicket of algae where she lays numerous small clusters of eggs scattered about the vegetation. One or two males that remain in pursuit of her will quickly fertilize each cluster. It is believed that a female produces well over a thousand eggs each summer to help maintain this fish’s population.
When sitting in a boat in an area of shallow water, standing on a rock or dock along the shore, or walking along the edge of a beaver pond, you are likely to notice small schools of fish the length of a person’s pinky slowly swimming amongst the stalks of weeds that jut above the surface. If the water has a dark color to it, and the fish has a few noticeable stripes along its side and a brightly colored lower side that resembles the sky at sunset, the fish is the redbelly dace, a fish native to the waters here in the Adirondacks.
Illustration: Redbelly Dace, courtesy DEC.
A version of this story first appeared on the Adirondack Almanack in 2012.