Our dads at the Marine Discovery Centre have been very busy. We were lucky enough to welcome both Pot-Bellied Seahorse babies and Purple-Spotted Gudgeon eggs to the creature family this week. In each of these species of fish, the male is responsible for most of the care of the eggs. As the babies hatch, they are then on their own and begin to swim and feed immediately.
The Purple-Spotted Gudgeon is a critically endangered freshwater species in South Australia, so it is even more exciting that we are seeing their eggs. The female will lay the transparent and sticky eggs on the underside of rocks or logs in their freshwater habitat, or on the glass of the tank in our case. The male then guards the eggs and fans them with his pectoral and pelvic fins to keep them clean and ensure no sediment settles on them. After approximately 8 days the eggs hatch and tiny gudgeon fry are born at around 4mm long. We are hoping to catch the hatching of our eggs so that we can try and separate juveniles from other hungry freshwater fish in the tank.
Seahorse fathers care for the eggs in a pouch located on their belly; the female will transfer her eggs to his pouch in a mesmerising courtship dance. The male pot-bellied seahorse will incubate the eggs for around 1 month until they hatch, after which he gives birth to hundreds of little seahorse fry. These babies are only around 12mm long and are usually born at night to avoid predators including other hungry seahorses nearby. This means in a tank environment the fry must be separated from the adult seahorses as soon as possible to avoid being confused with the mysis and brine shrimp we feed them.
Our baby seahorses are separated in a clear container covered in fine mesh which floats in the adult seahorse tank. This allows us to observe and feed them, as well as allowing for fresh water circulated within the container. We feed them baby artemia; a type of crustacean that makes up the plankton eaten by seahorses in the ocean and is small enough for the baby seahorse’s tiny snout.
Unfortunately, all fish species have a high mortality rate in the first few weeks of life. This is due to the reproductive strategy of fish in which many eggs are produced, but young are not cared for. This is in contrast to animals including mammals and birds in which fewer eggs are produced but young are cared for by parents. Seahorse fry are susceptible to predation, changes in temperature and salinity, swallowing air into pockets in the body disrupting buoyancy, and being swept away from feeding grounds by ocean currents. It is estimated that less than 0.5% of seahorse fry survive until adulthood, so we are doing all we can to assist in the survival of our beautiful babies.
For more information about baby seahorses read :https://core.ac.uk/download/pdf/41335684.pdf