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Where are three-spined sticklebacks found?

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Lined seahorse (Hippocampus erectus) — gasterosteiform Lined seahorse (*Hippocampus erectus*).

The three-spined stickleback (Gasterosteus aculeatus) is widely distributed throughout the Northern Hemisphere. These fish are found in a variety of aquatic environments, including fresh, brackish, and salt water.12