The pygmy seahorses comprise several species of tiny seahorse in the syngnathidfamily or Syngnathidae (seahorses and pipefish). Family Syngnathidae is part of order Syngnathiformes, which contains fishes with fused jaws that suck food into tubular mouths. They are found in Southeast Asia in the Coral Triangle area. They are some of the smallest seahorse species in the world, typically measuring less than 2 centimetres (0.79 in) in height.
The first pygmy seahorse known to science was Hippocampus bargibanti. At least six more species were named after 2000. The first species discovered lives exclusively on fan corals and matches their colour and appearance. So effective is pygmy seahorse camouflage that it was discovered only when a host gorgonian was being examined in a laboratory. Other species live on soft corals or are free-ranging among seagrasses and algae.
The pygmy seahorse is both tiny and well camouflaged. It is very difficult to spot amongst the sea grasses, soft corals, or gorgonians (sea fans) that it inhabits. Other distinctive pygmy seahorse characteristics include a fleshy head and body, a very short snout, and a long, prehensile tail. With their short snouts, they have the appearance of baby animals. Pygmy seahorses are 14–27 millimetres (0.55–1.06 in) long from the tip of the tail to the end of the snout, so that their vertical height while swimming is still smaller. An adult may be as small as 13 millimetres (0.51 in) long.