Squalius cephalus, the common chub, European chub or simply chub, The dorsal fin has 3 spines and 7–9 soft rays while the anal fin has 3 spines and 7–10 rays. The vertebrae count is 42–48. It can grow to 60 cm standard length but most fish are around 30 cm.
Eggs are round with a 1.8 mm diameter, and first day larvae are 6–7 mm long and weigh about 120 mg.
Distribution
The chub is distributed throughout most of northern Eurasia, it can be found in the rivers flowing into the North, Baltic, northern Black, White, Barents and Caspian Sea basins, the Atlantic basins south to Adour drainage in France and in Great Britain north to 56°, in Scandinavia in southern Finland and southern Sweden north to around Stockholm. In the Mediterranean basin it is found in France from the Var to the Hérault, and may also be present in the Aude and drainages. and Italy, but has been introduced to both countries. In Italy, S. cephalus is present and acclimatised since decades, but it seems marginally found here and there (mainly in the Po river basin), never forming well established populations.
Habitat and ecology
It is most abundant in small rivers and large streams in the "barbel zone" where there are riffles and pools. It occurs along the banks of slow-flowing lowland rivers in large lake and even in mountain streams. Chub in lakes undertake spawning migrations into inflowing streams. The adult fish are solitary but the juvenile fish are sociable and occur in shoals. The larvae and juveniles prefer rather shallow habitats along shorelines and these smaller fish have a varied diet of aquatic and terrestrial animals while the large, solitary adults prey mainly on freshwater shrimp and small fishes. and elderberry from trees overhanging the water. They feed throughout the year if there are opportunities, even in the coldest days of midwinter. where the age of fish can be assessed through by the number of rings that are visible in scales, these represent seasonal growth patterns.
Threats
Recent work has shown that chub ingest microplastic particles. Whereas many as 25% of sampled fish contained particles, these particles were not found in muscles. Many of the particles found were fibres that are released from clothes during washing, these are also ingested by macroinvertebrates such as Daphnia. Chub can also be contaminated by metal pollution such as copper, magnesium and sodium which can accumulate in tissues like the muscle, gills and liver. Young of the year fish contained particularly high levels of metal contaminants. though there are several over 10 lb on the Angling Trust's Top 50 list, which have been deprecated for various reasons. The European record is . The chub can reach a maximum length of 64–82 cm (24–31.5 in).
thumb|250px|German chub catch from the typical environment
Tackle and tactics
Smaller chub are not too difficult to catch and on small or medium-sized rivers, a stick-float fishing approach can be adopted or even a swim-feeder and using almost any bait including maggots, luncheon meat, sweetcorn and even small lures and flies. Chub also eat marine derived fishmeal-based pellets and diets of wild chub diets contain 44% of these pellets.