Dwarf Seahorse

The smallest of all seahorses fits in a teaspoon: Hippocampus zosterae averages 2 to 2.5 cm and rarely exceeds 5 cm. Like every syngnathid it has no scales and no tail fin, only an armour of bony rings and a prehensile tail that grips a blade of grass. Its colour shifts from white to tan, brown, yellow, green or black to match its perch, and Guinness World Records rates it the slowest fish alive, at roughly 1.5 m per hour. It ranges across the western Atlantic, from Bermuda and southern Florida to the Bahamas and the entire Gulf of Mexico, almost never leaving seagrass flats shallower than ten metres, where it anchors to the Zostera beds that gave it its species name. This is no reef fish but a lie-in-wait hunter of the meadows, picking off amphipods, copepods, shrimp larvae and fish fry that drift within reach. In the aquarium the rule is counter-intuitive: keep it small. Forty litres holds a dozen animals and keeps daily-hatched brine shrimp nauplii concentrated enough for constant grazing, whereas a large volume dilutes the prey and starves them. A species-only tank is essential, with a sponge filter that will not strain out the food, and water at 22-26 °C. Pairs are monogamous and the male broods 3 to 55 young for about ten days. Only for keepers who can hatch live food every single day.