Northern Tessellated Darter

Adults are usually 2 to 3 inches long, occasionally reaching 4 inches. Both the tessellated darter and johnny darter are rather pale with small, X- or W-shaped markings on the back and upper sides. Both have only a single anal fin spine whereas all other darters in their range have two. Tessellated darters have somewhat sharper snouts than johnny darters, more dorsal soft rays, and more pectoral fin rays. The suborbital sensory canal is complete in most tessellated darters, usually broken into two sections in johnny darters. Their nape is usually naked, and their cheeks are partly too completely scaled. The breast is usually naked and the belly partly scaled. The body of the tessellated darter is elongate, but a little compressed. In breeding males, the spines have fleshy knobs although they are not as well developed as in the fantail darter.

Tessellated darters eat crustaceans and small insects when they are small, gradually shifting to larger insects as the fish get bigger. Male tessellated darters guard nests of fertilized eggs until the fry (young) are free-swimming, and have been observed to engage in alloparental (adoptive) care of previous nest inhabitants' eggs. Alloparental care is associated with increased male reproductive success in this species. Males frequently engage in filial cannibalism (consumption of their own offspring).