The following information about the H. hippocampus was sent to us by one who has specialize in surveying them, and working with them for the last 8 years, Mr. Neil Garrick-Maidment. FishNth thanks Mr. Neil Garrick-Maidment for his contribution to the knowledge of this seahorse!
"H.hippocampus is found mainly along the south coast of Britain and then down along the same range as H.guttulatus. They can be any colour of the rainbow and individuals have been brought up in our waters bright orange, purple etc. Fully grown they are up to 5 inches. Both species are found in the same waters and coexist due to the varying snout lengths and the foods they target."
The former information provided to me about this seahorses is as follows:
H. Hippocampus is a 4-5" seahorse. Their range is all around the top of Africa and edges of Europe. They are usually brown, with black small markings. They are found where H. Ramulosus grows, the Western European cost, around the Mediterranean, and the Eastern tip of England, as well as the coasts of France, Belgium, and Holland.