Bitterling
Otolith description
Otoliths of cyprinidae are very hard to determine to species level. The otoliths are all round with a remarkable horseshoe shaped sulcus that is directed downwards. The margins are jagged and indented at the ostium.
Five species have otoliths that tend to be somewhat different from the others. Tench Tinca tinca tends to be more oval shaped instead of round, compared to the other cyprinidae. On gudgeon Gobio gobio otoliths the margins tend to be smoother, probably because this is only a small fish and the otoliths are not well developed. Bitterling Rhodeus sericeus is the smallest of the cyprinidae and otoliths are not well developed either. They are smoother at the margins and the sulcus is hardly visible. Roach Rutilus rutilus otoliths have a posterior end that tends to be straight instead of round. The otoliths of rudd Scardinius erythrophthalmus are more jagged and pointed at the ventral margin.
Sizes of otoliths:
gudgeon, bitterling: <2,5 mm
silver bream, roach, rudd: <8 mm
tench, bream, ide: <10 mm
carp: otoliths > 10 mm are always carp otoliths
When eroded the otoliths of all cyprinidae are smoothed, but the sulcus remains visible.
Cyprinidae are a family of fish that have well developed pharyngeal teeth and chewing pads. These are very useful for specific identification of the different fish species (Wheeler, 1978, Veldkamp, 1994, 1995), also because these fish remains are less vulnerable to erosion by the stomach acid.
Pharyngeal teeth description
Pharyngeal teeth of bitterling have one row with 5 teeth. The teeth are hooked.
Chewing pad description
Not available yet.
Fish length and distribution
Bitterling can grow up to 10 cm. Bitterling is a freshwater fish that is found in clear non-flowing waters. It is depended on fresh water mussels Anadonta spp. and Unio spp. for its breeding. It deposits the eggs in the musselshell. (Wheeler, 1978, Nijssen and De Groot, 1987).
Bitterling is found throughout Europe but because of its dependence on fresh water mussels it is only common locally.
Sample origin
Central part of the Netherlands.