The life history of the teardrop darter [Etheostoma (Catonotus) barbouri Kuehne and Small] was intensively studied from September 1972 through August 1973. A total of 299 teardrop darters were seined from two isolated populations in Alexander and Little Muddy creeks, Kentucky. These darters are known only to occur in second-, third-, or fourth-order tributaries of the Green River in Kentucky and Tennessee, and normally seek protection afforded by rocky or vegetated edges of such streams. Gonosomatic ratios indicated that teardrop darters spawned from late March through late May in waters of 12.5-15.5 C. Young females developed mature ova at a later date than did their older counterparts. Fry were first collected in late May in shallow riffles. Longer fish produced a greater number of mature eggs than did the shorter fish. Males were the predominant older fish with few females surviving to their 2nd birthday. Length-frequency distributions and scale annuli readings indicated three age groups -0, I and II. Average standard lengths at the ends of these age periods were 30, 41 and 46 mm. Darters gained the greatest percentage of weight during the 2nd year of life. The faster-growing fish of Little Muddy Creek were shorter-lived than the slower-growing fish of Alexander Creek. The length-weight regression values of all fish, except female and nonsexed fish from Little Muddy Creek, were greater than 3.0. Coefficients of condition, lowest in the autumn and highest in the spring months, indicated that slowergrowing fish were slightly more plump than were the faster-growing fish. Teardrop darters were carnivorous throughout life. The most commonly ingested food items were cladocerans, chironomids, copepods and simuliids. Chironomid larvae were the food items most frequently ingested. Cannibalism was observed. Spring and winter months were periods of heaviest feeding. Over one-half of the darters collected had black-spot Neascus of Crassiphiala bulboglossa, while about 7% had internal mesentary nematodes, probably Contracaecum sp. INTRODUCTION The teardrop darter (Etheostoma barbouri Kuehne and Small) was described in 1971 as a member of the subgenus Catonotus, and is known to occur only in the Green River basin of Kentucky and Tennessee. The subgenus Catonotus includes three species-groups, the spottail darter (Etheostoma squamiceps Jordan), the fantail darters [E. flabellare Rafinesque and E. kennicotti (Putnam)], and the barcheek darters [E. virgatum (Jordan), E. striatulum Page and Braasch, E. obeyense Kirsch, E. smithi Page and Braasch and E. barbouri Kuehne and Small] (Page, 1975a). Etheostoma barbouri differs from the other barcheek species in having a stronger suborbital pigment bar, nine preoperculomandibular pores and a lower number of infraorbital and lateral-line pores (Kuehne and Small, 1971; Page and Braasch, 1976 and 1977). Due to the small number of specimens available for this study, teardrop darters were taken from populations in two different streams. Because Kuehne and Small (1971) noted meristic variation between specimens from the Green-Nolin River drainage and those from the Barren River drainage, a population was selected from one stream in each of these drainages. The intensive study of these two local populations, including details of range and habitat, reproduction, age and growth, food habits, parasites and predators, followed the suggested format of Koster (1955). MATERIALS AND METHODS Physical and chemical parameters were measured at each stream station imme1 Present address: 302 North 17th Street, Mayfield, Kentucky 42066.