Grass Carp
  • Side view adult.
  • Side view adult.
  • Side view adult.
  • Top view adult.
  • Bottom view adult: The belly is split open and the viscera is removed.
  • Head-on view adult.
  • Close-up flank.
  • Close-up head.
  • Close-up mouth and snout.
  • Close-up tail.
  • Close-up dorsal fin.
  • Close-up anal fin: The fin membranes are partially split in two places.
  • Close-up pectoral fin: The belly is split open and the viscera is removed.
  • Close-up pelvic fin: The belly is split open and the viscera is removed.
  • Close-up ventral area: Notice the absence of a ventral keel; the belly is split open and the viscera is removed.
  • There are 15-16 gill rakers.
  • The grass carp has a fusiform body and 34-47 lateral line scales.
  • Close-up mouth: The mouth is terminal, there are no barbels.
  • Close-up dorsal fin: Notice the lack of a spine, there are 7-9 dorsal rays.
  • Close-up anal fin: Notice the lack of a spine, there are 8-10 anal rays.
  • Side view of a young-of-year: They are similar to adults except for a somewhat more elongated body and proportionally bigger eyes.
  • Side view of a yearling: They are similar to adults.
  • The intestines are spiraled and greatly elongated.
  • Alternate side view.
DescriptionSimilar Species
Family
Minnows (Cyprinidae)
Body
Mouth and Snout: Mouth terminal without any teeth. No barbels. Body Pattern: Solid light olive to silvery white on body, with head and fins more darkly pigmented. Obvious cycloid scales, outlined in dark pigment giving the sides a cross-hatched appearance. Body Shape: Fusiform. Typical adult size is 400-700 mm TL (1.3-2.3 ft), with a maximum of about 1300 mm (4.3 ft).
Fins
Forked tail. Single short dorsal fin without any spines. Pelvic fins abdominal. No adipose fin. Anal fin without spike and with 8-10 rays.
Distinguishing Characteristics
Fusiform body with no ventral keel. Dorsal fin with 7-9 soft rays and anal fin with 8-10 soft rays. Terminal mouth without barbels. 34-47 lateral line scales and 15-16 gill rakers. See also similar species information.
Breeding Adults
Breeding males have small tubercles on the pectoral fins.
Juveniles
Similar to adults.
Hybrids
None known from Wisconsin.
Compare Similar Species
Body Shape
Buffalo, BigmouthDeep, laterally compressed
Buffalo, BlackDeep, laterally compressed
Buffalo, SmallmouthDeep, laterally compressed
Carp, BigheadFusiform
Carp, CommonDeep, laterally compressed
Carp, GrassFusiform
Carp, SilverFusiform
Carpsucker, HighfinDeep, laterally compressed
Carpsucker, RiverDeep, laterally compressed
GoldfishDeep, laterally compressed
QuillbackDeep, laterally compressed
Ventral Keel
Buffalo, BigmouthAbsent
Buffalo, BlackAbsent
Buffalo, SmallmouthAbsent
Carp, BigheadFrom anal fin to pelvic fin
Carp, CommonAbsent
Carp, GrassAbsent
Carp, SilverFrom anal fin to isthmus
Carpsucker, HighfinAbsent
Carpsucker, RiverAbsent
GoldfishAbsent
QuillbackAbsent
Mouth
Buffalo, BigmouthTerminal, subterminal or inferior
Buffalo, BlackTerminal, subterminal or inferior
Buffalo, SmallmouthTerminal, subterminal or inferior
Carp, BigheadTerminal
Carp, CommonSubterminal
Carp, GrassTerminal
Carp, SilverTerminal
Carpsucker, HighfinTerminal, subterminal or inferior
Carpsucker, RiverTerminal, subterminal or inferior Terminal, subterminal or inferior
GoldfishTerminal
QuillbackTerminal, subterminal or inferior
Barbels
Buffalo, BigmouthAbsent
Buffalo, BlackAbsent
Buffalo, SmallmouthAbsent
Carp, BigheadAbsent
Carp, CommonPresent
Carp, GrassAbsent
Carp, SilverAbsent
Carpsucker, HighfinAbsent
Carpsucker, RiverAbsent
GoldfishAbsent
QuillbackAbsent
Dorsal Fin
Buffalo, Bigmouth22-32 rays; first few rays elongated
Buffalo, Black22-32 rays; first few rays elongated
Buffalo, Smallmouth22-32 rays; first few rays elongated
Carp, Bighead1 spine in adults, 8 rays
Carp, Common1 serrated spine, 15-23 rays
Carp, Grass7-9 rays
Carp, Silver1 spine in adults, 8 rays
Carpsucker, Highfin22-32 rays; first few rays elongated
Carpsucker, River22-32 rays; first few rays elongated
Goldfish1 serrated spine, 15-19 rays
Quillback22-32 rays; first few rays elongated
Anal Fin
Buffalo, Bigmouth7-10 rays
Buffalo, Black7-10 rays
Buffalo, Smallmouth7-10 rays
Carp, Bighead1 spine in adults, 13-14 rays
Carp, Common1 serrated spine, 4-6 rays
Carp, Grass8-10 rays
Carp, Silver1 spine in adults, 12-13 rays
Carpsucker, Highfin7-10 rays
Carpsucker, River7-10 rays
Goldfish1 serrated spine, 5-6 rays
Quillback7-10 rays
Lateral Line Scales
Buffalo, Bigmouth33-40
Buffalo, Black33-40
Buffalo, Smallmouth33-40
Carp, Bighead85-100
Carp, Common32-41
Carp, Grass34-47
Carp, Silver95-103
Carpsucker, Highfin33-40
Carpsucker, River33-40
Goldfish27-30
Quillback33-40
Gill Rakers
Buffalo, Bigmouth20-70
Buffalo, Black20-70
Buffalo, Smallmouth20-70
Carp, Bighead53-80; long and fine
Carp, Common21-27
Carp, Grass15-16
Carp, SilverFused into sponge-like matrix
Carpsucker, Highfin20-70
Carpsucker, River20-70
Goldfish37-43
Quillback20-70
Similarity Index
Buffalo, BigmouthModerately similar
Buffalo, BlackModerately similar
Buffalo, SmallmouthModerately similar
Carp, BigheadModerately similar
Carp, CommonModerately similar
Carp, GrassN/A
Carp, SilverModerately similar
Carpsucker, HighfinModerately similar
Carpsucker, RiverModerately similar
GoldfishModerately similar
QuillbackModerately similar
Comments
Carp, BigheadNot yet confirmed from WI waters (two anecdotal records), but well-established further south in the Mississippi River and likely to be encountered in WI in the future.
Carp, GrassNot established in WI; present only as a stray from further south or from illegal introduction
Carp, SilverNot yet confirmed from WI waters, but well-established further south in the Mississippi River and likely to be encountered in WI in the future.
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