Young long-snout seahorses (Hippocampus reidi) are nine months old now. The team of the Department of Russian Far East Marine Species kept their triumph under wraps for an understandable reason: while seahorses breed readily, the survival rate of the offspring is very low, both in the wild and in captivity.
All the previous breeding attempts with these exotic fish had failed. Now, having navigated past all critical developmental stages, the keepers can breathe a sigh of relief. As it turned out, there are several vulnerable key phases in seahorses’ early life. Some fry may swallow air bubbles upon emerging from their father’s brood pouch*, which pins them to the surface where they starve to death. Others never begin feeding properly. One more cause of low survival rate in fry is that they are highly susceptible to bacterial and fungal infections.
Despite these hurdles, the Primorsky Aquarium’s specialists have reached their goal. Their success stems from meticulous care: constant monitoring for the presence of uneaten food or faeces on the bottom, intensive cleaning of aquariums as needed, daily water sampling, fine-tuning UV light intensity, and providing the perfect live food for the minuscule fry—specifically, rotifers and brine shrimp nauplii. Today, several whimsical fish resembling chess pieces playfully swim in a small aquarium within the Science and Acclimation Building.
“Our younger seahorses are now more or less the same size as the adults and will soon be able to become parents themselves,” said Anatolii Sokolov, Senior Specialist in the Department of Russian Far East Marine Species. “They are in excellent health and have great appetites. As seahorse fry grow, their required food size changes. It had been creating difficulties before, because local waters do not offer such a variety of zooplankton as tropical seas, so we started improvising. Now our young seahorses eat brine shrimp cultivated by the Aquarium’s Live Food Section and frozen mysids. In most public aquariums, frozen food is part of a common diet for adult fish because providing a constant supply of live prey is incredibly difficult. Their peculiar physiology makes seahorses continuous feeders. With no teeth or stomach, the fish literally suck food directly into their intestines. A full digestive cycle takes about three hours of non-stop feeding. A single seahorse can consume thousands of tiny crustaceans in a day.”
There are over 50 known seahorse species inhabiting world’s tropical and temperate waters, but most of them are listed as “vulnerable” or “endangered” and need protection. Thus, every successful captive breeding program is crucial for their conservation. The news that the seahorse young ones successfully reached the age of nine months have become a perfect New Year’s gift for the entire Aquarium staff. The timing felt especially symbolic: the team announced their triumph on the eve of the new 2026 year, which is the Year of the Horse in the Chinese calendar.
*In seahorses, it is the father who carries the offspring. The female transfers her eggs into the male’s brood pouch, then the male fertilizes and incubates them for approximately 40 to 60 days.
