Bryan Kent, senior Aquarium biologist, holds the future of many fish babies in his hands – hundreds of them, in fact.
Two breeding pairs of rock greenling (Hexagrammos lagocephalus) and four golf ball-sized egg masses have been keeping him busy.
This is a rock greenling egg under a microscope. Notice its black eyes and curled tail.
He had his first inkling that rock greenling babies were on their way when he noticed a pregnant (gravid) female in the Treasures of the B.C. Coast gallery. Soon after, he saw a male rock greenling guarding eggs along the rockwork near the surface of the water. Yes, in the fish world, it’s not unusual for dad to do almost 100 per cent of the egg care.
When the eggs are close to hatching, Bryan will take them out of the exhibit and keep them behind the scenes. In the ocean, the eggs and babies (fry) are likely to get eaten by other animals, and in this exhibit, they can also get accidentally sucked out via the filtration system.
The male rock greenling is on the left, while the less colourful female is on the right.
Bryan says that discovering the rock greenling eggs was exciting because it’s rare for there to be breeding pairs at the Aquarium, so they haven’t had the chance to rear them yet. However, Aquarium biologists and fish lab researchers have successfully reared other greenling species, such as the kelp (H. decagrammos), whitespotted (H. stelleri) and painted (Oxylebius pictus) greenlings.
Rock greenlings are found along the northwest Pacific coast through to Russia. They live in rocky reefs, eating worms, crustaceans and small fishes. Despite the males’ vibrant colours, they actually blend in well among the surrounding rocks and seaweed.
Rearing fish is a precarious undertaking, but it’s a challenge that Bryan has embraced, judging from the set up of equipment behind the scenes meant to give the eggs (and anticipated fry) the best chance for survival.
Written by Karen Horak, writer-editor, content and digital experience at the Vancouver Aquarium.
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