Thursday, October 30, 2008

Goldfish External Anatomy

                                Goldfish External Anatomy

Anal Fins: Helps to keep the fish stable in the water and keep it from from rolling over.

Caudal Fins: Tail fins are used for propulsion (to push the fish forward). Goldfish are bred to have many different types of tailfins. Common goldfish have single tails and the fancy goldfish have different types of double tails.
Caudal Peduncle: Where the tail meets the body.
Dorsal Fin: provide stability when swimming. Wild type goldfish (and most common goldfish) will have a long dorsal with about 13-19 rays. The rays starts like spines and branch out at the end. Not all goldfish breeds have dorsal fins. Ranchu and Lionheads are two of the most common breeds without this fin. Some veiltail varieties have a very tall dorsal fin. For fish with a dorsal fin, this this fin should be erect (a sign of good health), however in some breeds with tall dorsal fins, the dorsal will bend.

Eyes: Goldfish use their eyes to see. Goldfish have fairly good eyesight. Some breeds however are bred to have "bug eyes" (i.e. telescope goldfish like moors) and cannot see that well. Some people believe that black goldfish are normally almost blind. Fish do not have eyelids, so you should turn your tank lights off every evening so they can get some sleep.

Lateral line: Is a sensory organ (a series of fluid-filled canals just underneath the skin) that helps fish detect water current, pressure and movement.

Mouth: The mouth opens at anterior end of head. The upper and lower jaws are equal in size and are slightly slanted. Golfish don't have barbels. Goldfish do not have teeth in their jaws, but they do have pharyngeal teeth found in the back part of the oral cavity.
Nares: There are two pairs of nares on each side of the snout. The front and rear nares are connected by a U shaped tube. Water flows through the nares through the olfactory tube and receptors embedded in the epithelium detect odors in the water. Behind the front nares, there may be a flap of skin called the narial folds or nasal septa which directs water into the front opening. Pompon goldfish are known for their large frilly narial folds or nasal septa.
Operculum: The flap covering the gill also known as gill cover. Males will develop small white spots on the gill cover which are called breeding stars or breeding tubercles. Breeding stars are not seen until the goldfish is old enough to breed, somewhere between the age of two and three years. Some goldfish are bred to have curled operculums.
Pectoral Fins: The two pectoral fins are used for steering. Male goldfish, when they reach sexual maturity will often develop white bumps called nuptial tubercles or breeding stars along the leading ray of their pectoral fins. Some people say that the first ray of the pectoral fin is rather thick and stiff in male golfish (compared to those of female goldfish). Some people also believe that male goldfish have longer pectoral fins that do female goldfish. If the goldfish is ill, it may clamp the pectoral fins close to its body.

Pelvic/Ventral Fins: The two pelvic fins provide stability and help with steering. For breeders the shape and length of the vental fin is very important. Japaneese breeders in particular often specialize in fish with long ventral fins.

Vent: (or anal opening) External opening to digestive, urinary and reproductive tracts. Some people believe that females have rounder covex vents while males have thinner concave vents. During spawning, male golfish will try to butt the female anal area.

Wen: Rasberry-like growth (skin folds) on top of the head of some breeds of goldfish such as orandas, and lionheads. Sometimes also known as a hood, cap, crown or goosehead. As the wen grows, white pimples may sometimes occur. These are generally nothing to be concerned about.
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