Charlebois et al. (1997) describe N. melanostomus in detail as, \"scaled on the parietal region, nape, back (all), throat (all or most), abdomen, pectoral fin peduncles, and one quarter of the gill covers. Scales on the middle and anterior nape are cycloid (as are scales on the greater part of the gill covers and throat, pectoral peduncles, and part of the abdomen [Rudnicka, personal communication]). The head is as wide as or wider than deep; depth is 0.9-1.2 times the width. Head length is 22-23% of total body length. There are usually six, rarely seven, transverse suborbital series of pit organs. Ventral fins reach or almost reach the vent. The pelvic disk is 0.6-0.8 times the abdomen length. If present, the anterior membrane width is very shallow, with rounded, lateral lobes. The caudal peduncle depth is about two-thirds its length. The anterior dorsal fin has five to seven spines, usually six, and the posterior dorsal fin has one spine and 13-16 soft rays. The anal fin has one spine and 11-14 soft rays, and the pectoral fins have 17-20 soft rays N. melanostomus possesses upper and lower pharyngeal teeth, and the posterior teeth are smaller than anterior teeth (Pinchuk, 1992; Ghedotti et al., 1995). N. melanostomus lacks a gas bladder and chemoreceptors.\"

Charlebois et al. (1997) go into great detail on the specific habitat preference of N. melanostomus. The authors state that, \"N. melanostomus occur on coarse gravel, shell, and sand in inshore areas to depths of 20m in the Black Sea and the Sea of Azov (Miller, 1986). In the Caspian Sea, N. Melanostomus occur to 70 m, and are often associated with eelgrass (Zostera sp.) (Moskal'kova, 1996). In the Kuybyshev Reservoir, N. Melanostomus occur in silted sand at depths of 5-10m and in river beds to 30m (Tsyplakov, 1974). N. Melanostomus also occur in lower and middle reaches of rivers, but only in slightly brackish or fresh water (Miller, 1986, but see \"Physiology\" section). During spring-autumn in the Black Sea, N. Melanostomus is found in slowly flowing rivers, lagoons, and brackish coastal water to 20m (Jude and DeBoe, 1996), but it migrates to deeper water (50-60 m) in winter (Miller, 1986). During spring, N. Melanostomus migrates to inshore areas of the northern Caspian Sea even while these areas are still partially frozen (Nikol'skii, 1954). N. Melanostomus prefers littoral areas where wave action maintains high dissolved oxygen levels and reduces the amount of decaying material. In the Gulf of Gdansk, N. Melanostomus is associated with stone/sand areas, mussel beds, marine structures, and sunken objects. In Puck Bay, Gulf of Gdansk, N. Melanostomus inhabits areas with a humus/mud/sand substratum overgrown with benthic flora (Skora, 1996)\".

Charlebois et al. (1997) state that in its introduced range, \"In the St. Clair River, N. Melanostomus are associated with large cobble to depths of 3m and macrophytes (e.g., Elodea canadensis, Myriophyllum spp. And Potamogeton spp.) in depths of 1.5-4.6 m. They also have been impinged on industrial screens at 6m depth (Jude et al. 1992; Jude et al. 1995; Jude and DeBoe, 1996). Fry were collected in Chara beds presumably where spawning occurred (Jude et al. 1995). Macrophytes and cobble provide large interstices for refuge and spawning (Jude and DeBoe, 1996), but N. Melanostomus apparently is not restricted to these habitats (Jude et al. 1992; Jude and DeBoe, 1996; MacInnis and Corkum, 2000). In Calumet Harbor (Illinois), N. Melanostomus were abundant on both cobble and sand, although adults were less abundant on sand than juveniles. N. Melanostomus also will move onto sandy beaches to feed at night (Jude et al. 1992). In the St. Clair River, there is an inverse relationship with depth and number of N. Melanostomus, but a direct relationship with depth and length of individuals, which may be due to gear bias (Jude et al. 1995). N. Melanostomus were not collected in shallow near shore areas of Lake St. Clair until May 8 in 1993 (T. Water =7.8ºC), but were abundant from shore to 5m on November 5, and in December trawls at 3, 5, and 7 m.\"

Charlebois et al. (1997) state that, \"N. melanostomus is a benthic feeder. Its diet is composed primarily of crustaceans and molluscs, including zebra mussels. Polychaetes, small fish, goby eggs, and chironomid larvae also are eaten (Berg, 1949; Miller, 1986). In the Sea of Azov, N. melanostomus was the primary consumer of benthos, consuming up to 13% of the annual production. Its diet during the primary feeding period (spring-fall) was 90% molluscs, and during winter was 11-41.8% fish (mainly Clupeonella; Skazkina and Kostyuchenko, 1968). N. melanostomus of all sizes eat molluscs and crustaceans. Small- and medium-sized N. melanostomus also eat worms (presumably polychaetes), but only larger individuals eat other fish (Skazkina and Kostyuchenko, 1968; Kovtun et al. 1974). In North America, N. melanostomus also primarily consume benthic organisms. Other items in the stomachs were Gammarus, Ceratopogonidae, Ephemeroptera (Caenis, Stenonema, Ephemera, Hexagenia , Baetis), Odonata (Macromia), Diptera (Atherix pupae and larvae), Oligochaeta, Ostracoda, Decapoda (crayfish), and Trichoptera. Larger fish contained more chironomids and zebra mussels than smaller fish. N. melanostomus ingests zebra mussels intact; divers in the St. Clair River have observed N. melanostomus wresting zebra mussels from the substratum and swallowing them whole (Johnson and Lashbrook, 1993). N. melanostomus generally crushes the zebra mussels with its pharyngeal teeth, and shells are discarded before the soft body is swallowed (Ghedotti et al. 1995).\"