My grandson loved watching the Lined Seahorses at the Georgia Aquarium. The sign next to their tank said that seahorses are disappearing due to overharvesting and that we should avoid buying seahorses for any purpose unless they are cultured or certified as sustainably collected. Seahorses are true fish, with a backbone, gills and scales. The male seahorse incubates eggs in a pouch just below its abdomen. Seahorses grow to a maximum size of 7.5 inches or 19 cm.