Aquatic Invasive Fish Species: Rudd
Volume 4, Issue 4
There are at least 30 exotic fish species currently in Maine. Golden shiners (top) are native to Maine; rudd (bottom) are exotics from Europe. It is very difficult to tell the two fish species apart. Taxonomically they are indistinguishable except for their pharyngeal teeth. Rudd are an exotic invasive species that may cause damage to native fisheries. Rudd can grow to be much larger than golden shiners, they can interbreed with golden shiners, and they can replace native fish species. It is illegal to import or use rudd as bait in Maine-be certain that you can tell them apart.
TAXONOMIC CHARACTERISTICS: Paired fins, jaw present, one external gill opening on each side of body, caudal fin homocercal, pelvic fins present, adipose fin absent, belly round, having no keel, no serrate margin, having no imbricated scutes, snout not duckbill shaped, anus located just anterior to anal fin, one dorsal fin present, caudal fin forked, dorsal fin with 9 or less fin rays, branched caudal fin rays, and pharyngeal arch with 6 or less teeth in major row (inner).
Dorsal fin lacking spines, pre-anal distance less than 3x as long as post anal distance, lower jaw lacking hard ridge along anterior edge; intestine not fully enwrapping gas bladder, lower jaw and lip normal, barbel absent, mouth and lips not sucker like, mid-ventral body between pelvic and anal fins with a largely non-scaled low ridge, mouth small sharply upturned; body much compressed; dorsal fin origin moderately or much posterior to pelvic fin base; 40 scales along lateral line (lateral line in rudd appears more arched ventrally than the golden shiners), anal fin moderately or strongly falcate:
Species: RUDD, Scardinius erythrophthalamus pharyngeal teeth 3,5-5,3;
Species: Golden shiner Notemgonus crysoleucas pharyngeal teeth 0,5-5,0
Special points of interest:
It is illegal to import bait fish into Maine.
It is illegal to use rudd as bait.
If you cannot tell golden shiners from rudd, do not use the fish as live bait.
For more information read: Fuller, 2000. Nonindigenous Fishes, American Fisheries Society Press.