If you carefully analyse the fish in your aquarium, you would see a skeleton inside its body. The parts of the skeleton are a skull, backbone and fin supports. The skull of a fish has a cranium, and visceral arches. The bony cover that surrounds, and protects the brain is called the cranium. The visceral arches in the body of a fish support of its gills. These arches are also called the gill arches.
The backbone of a fish is series of disc like bones. The backbone protects the spinal cord of the animal. There are thin, needle-like ribs that extend from the backbone toward the belly. This structure supports the entire body of a fish.
Many fins are found in the body of a fish. Each fin has a large support at its base. They have two sets of fins, which are paired. One pair is called the pectoral fins, which lie just behind the head, one on both sides; and the other pair is called the pelvic fins, which may be far back on the body or under the head. The pelvic fins are smaller than the pectoral fins and are always on the belly side of the fish. Other fins of the fish are generally un-paired. It means that there is only one of each. The dorsal fin is found at the centre of the back of the fish. Fishes have an anal fin on the belly side too, just in front of the tail. The tail of the fish is called the caudal fin.
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