DeJong Breeds the Flathead Perch, Rainfordia opercularis
Dutch marine livestock supplier DeJong has successfully bred and raised Flathead Perch in captivity.
Flathead Perch are known primarily as collector’s fish, previously commanding prices of £5000 or more.
Since being tank-bred, the price has come down, with US-based breeder Biota selling them for $1000, or £750.
Despite this, DeJong are only the third organisation worldwide who has managed to breed them successfully in captivity, (and the first in Europe,) and it’s a huge achievement.
The only member of its genus, Rainfordia opercularis is so-named after Edward Henry Rainford (1853–1938) ,an English-born Australian amateur naturalist who collected specimens of fauna and flora for the Australian Museum.
Once thought to be Western Australian endemics, they have since been found on the Great Barrier Reef and Indonesia, but we’ve still only seen maybe three in the flesh in the past 15 years, and only one of them was in the UK.
An acquired taste, these dorsoventrally compressed basslets are made for wedging into tight crevices and predating the small fish and shrimp they find within them. Occupying rockwork at depths up to 40 metres, they are described as scarce in the wild (and hard to find, hence the price,) but now, expect to see a lot more of them in the future.
Flathead perch are coral safe, but may eat small fish and shrimp. They attain a maximum size of 15cm/6” and it goes without saying that they should be provided lots of caves, rocks and crevices to hide amongst, and subdued lighting.
Here’s what DeJong had to say about their latest success:
“We are incredibly proud to announce the successful captive breeding and larval rearing of Rainfordia opercularis, commonly known as the Flathead Perch. To the best of our knowledge, De Jong Aquaculture is only the third facility in the world to successfully breed and raise this remarkable species in captivity.
The first documented success was achieved by marine biologist Todd Gardner in 2016, followed by the Batavia Coast Maritime Institute in Western Australia in 2019. We are proud to add De Jong Aquaculture to this short list of successful breeding programmes.
Native to Australian reefs, the Flathead Perch is a secretive, cave-dwelling species rarely encountered by divers and highly sought after in the marine aquarium trade. Its successful captive propagation presents significant challenges, particularly during the larval stage.
One of the greatest challenges is its exceptionally long pelagic larval phase, exceeding 40 days. Successfully rearing the larvae throughout this prolonged developmental period required carefully controlled conditions, specialized feeding strategies, extensive observation and considerable patience.
During development, we observed one particularly extraordinary feature: extremely elongated dorsal-fin filaments. At one stage, these measured an astonishing 38 cm in a larva less than 2 cm long.
The function of these remarkable filaments remains unknown. Their resemblance to jellyfish tentacles raises the possibility of a mimicry function, although this hypothesis has yet to be confirmed.
The accompanying photographs document this fascinating transformation, from tiny, transparent eggs and delicate larvae with their extraordinary fin filaments to developing juveniles gradually acquiring the characteristic appearance of the species.
For us, this achievement represents more than the successful breeding of a rare fish. Every species we learn to reproduce in captivity expands our understanding of marine reproduction, larval development and species-specific husbandry, contributing to a more sustainable future for the marine aquarium industry.
We are extremely proud of this milestone and look forward to sharing more of our observations with the international marine aquaculture community.”
Image credits and more information DeJong MarineLife
