Dorsal fin

This is a single (not paired) fin located on the fish’s back. Some fish may have only one dorsal fin while others may have two or even three. In many fishes, dorsal fin has stout spines in the front to help give the fin support.

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Adipose fin

This fin is found or such fish as the catfish and trout. It does not serve much of a purpose. It is probably just part of an ancient fin that was once found on the fish’s ancestors.

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