Crucians are commonly confused with wild goldfish,and unfortunately many waters have been sold "crucians" that are really goldfish, or goldfish x crucian hybrids.Put the two side by side, and it can be seen that the crucian has many small scales, whereas the goldfish has larger but fewer scales. The lateral line count of a crucian is 31 to 35 scales, whilst that of the goldfish is typically 25 to 30. Another difference is the snout - which is carp-like (ie it protrudes) in the goldfish, but has a very steep upward slope of the lower jaw in the case of the crucian - giving a very flat stubborn-looking chin when the mouth is closed.
Crucians can also hybridise with common carp, but any such hybrid will show barbules at the corner of the mouth. No matter how small, the presence of such barbules mean the fish is NOT a true crucian.
Crucians can vary slightly in colour, but the classic true crucian has a brassy sheen to its flanks and the lower fins are a deep reddish colour. The dorsal fin in the crucian tends to have a slightly convex outer edge, whereas in both goldfish and common carp the edge is concave.Dave Park 05:10, September 22, 2010 (UTC)