The Johnny Darter

Teacher’s Story

“We never tired of watching the little Johnny, or Tessellated darter (Boleosoma nigrum), although our earliest aquarium friend, (and the very first specimens showed us by a rapid ascent of the river weed how ‘a Johnny could climb trees,’) he has still many resources which we have never learned. Whenever we try to catch him with the hand we begin with all the uncertainty that characterized our first attempts, even if we have him in a two-quart pail. We may know him by his short fins, his first dorsal having but nine spines, and by the absence of all color save a soft, yellowish brown, which is freckled with darker markings. The dark brown on the sides is arranged in seven or eight W-shaped marks, below which are a few flecks of the same color. Covering the sides of the back are the wavy markings and dark specks which have given the name of the “Tessellated Darter;” but Boleosoma is a preferred name, and we even prefer ‘boly’ for short. In the spring the males have the head jet black; and this dark color often extends on the back part of the body, so that the fish looks as if he had been taken by the tail and dipped into a bottle of ink. But with the end of the nuptial season this color disappears and the fish regains his normal, strawy hue.

His actions are rather bird-like; for he will strike attitudes like a tufted titmouse and he flies rather than swims through the water. He will, with much perseverance, push his body between a plant and the sides of the aquarium and balance himself on a slender stem. Crouching catlike before a snail shell, he will snap off a horn which the unlucky owner pushes timidly out. But he is also less dainty and seizing the animal by the head, he dashes the shell against the glass or stones until he pulls the body out and breaks the shell.”—David Starr Jordan.

The johnny darters are, with the sticklebacks, the most amusing little fish in the aquarium. They are well called darters since their movements are so rapid when they are frightened that the eye can scarcely follow them; and there is something so irresistibly comical in their bright, saucy eyes, placed almost on top of the head, that no one could help calling one of them “Johnny.” A “johnny” will look at you from one side, and then as quick as a flash, will flounce around and study you with the other eye and then come toward you head-on so that he may take you in with both eyes; he seems just as interested in the Johnny out of the jar as is the latter, in the johnny within.

The johnny darter has a queer shaped body for a fish, for the head and shoulders are the larger part of him; not that he suddenly disappears into nothingness, by no means! His body is long and very slightly tapering to the tail; along his lateral line he has a row of olive-brown W’s worked out in scale-mosaics; and he has some other scale-mosaics also following a pattern of angular lines and making blotches along his back. The whole upper part of his body is pale olive, which is a good imitation of the color of the brook.

The astonished and anxious look on the johnny darter’s face comes from the peculiar position of the eyes which are set in the top of his forehead; they are big, alert eyes, with large black pupils, surrounded by a shining, pale yellow line at the inner edge of the green iris; and as the pupil is not set in the center of the eye, the iris above being wider than below, the result is an astonished look, as from raised eyebrows. The eyes move, often so swiftly that it gives the impression of winking. The eyes, the short snout, and the wide mouth give johnny a decidedly froglike aspect.

Although he is no frog, yet johnny darter seems to be in a fair way to develop something to walk upon. His pectoral fins are large and strong and the ventral pair are situated very close to them; when he rests upon the gravel he supports himself upon one or both of these pairs of fins. He rests with the pectoral fins outspread, the sharp points of the rays taking hold of the gravel like toenails and thus give him the appearance of walking on his fins; if you poke him gently, you will find that he is very firmly planted on his fins so that you can turn him around as if he were on a pivot. He also uses the pectorals for swimming and jerks himself along with them in a way that makes one wonder if he could not swim well without any tail at all. The tail is large and almost straight across the end and is a most vigorous pusher. There are two dorsal fins; the front one has only nine rays; these are not branched and are therefore spines; when the fin is raised it appears almost semi-circular in shape. The hind dorsal fin is much longer and when lifted stands higher than the front one; its rays are all branched except the front one. As soon as the johnny stops swimming he shuts the front dorsal fin so that it can scarcely be detected; when frightened he shuts both the dorsal fins and closes the tail and the anal fin and spreads out his paired fins so that his body lies flat on the bottom; this act always reminds one of the “freezing” habit of the rabbit. But johnny does not stay scared very long; he lifts his head up inquisitively, stretching up as far as he is able on his front feet, that is, his pectorals, in such a comical way that one can hardly realize he is a fish.

The tail and the dorsal fin of the johnny darter are marked with silver dots which give them an exquisite spun-glass look; they are as transparent as gauze.

The johnny darters live in clear, swift streams where they rest on the bottom, with the head up stream. Dr. Jordan has said they can climb up water weed with their paired fins. I have never observed them doing this but I have often seen one walk around the aquarium on his fins as if they were little fan-shaped feet; and when swimming he uses his fins as a bird uses its wings. There are many species of darters, some of them the most brilliantly colored of any of our fresh-water fishes. The darters are perch-like in form.

Dr. Jordan says of the breeding habits of the darters: “On the bottom, among the stones, the female casts her spawn. Neither she nor the male pays any further attention to it, but in the breeding season the male is painted in colors as beautiful as those of the wood warblers. When you go to the brook in the spring you will find him there, and if you catch him and turn him over on his side you will see the colors that he shows to his mate, and which observation shows are most useful in frightening away his younger rivals. But do not hurt him. Put him back in the brook and let him paint its bottom with colors of a rainbow, a sunset or a garden of roses. All that can be done with blue, crimson and green pigments, in fish ornamentation, you will find in some brook in which the darters live.”