Few fish are famed for their parenting skills. Most species leave their freshly hatched fry to fend for themselves, but not discus fish. Jonathan Buckley from the University of Plymouth, UK, explains that discus fish young feed on the mucus that their parents secrete over their bodies until they are big enough to forage. 'The parental care that they exhibit is very unusual,' says Buckley. Intrigued by the fish's lifestyle, Buckley's PhD advisor, Katherine Sloman, established a collaboration with Adalberto Val from the Laboratory of Ecophysiology and Molecular Evolution in Manaus, Brazil, and together with Buckley and Richard Maunder set up a colony of breeding discus fish to find out more about their strange behaviour. The team published their discovery, funded by the Leverhulme Trust, that discus fish parent their young like mammalian mothers on 29 October 2010 in The Journal of Experimental Biology at http://jeb.biologists.org/cgi/content/abstract/213/22/3787.
Unfortunately, discus fish are notoriously difficult to bred and keep in captivity. 'Hobbyists didn't succeed in rearing them until the 1970s,' explains Buckley. Having imported 30 adults from breeders in Malaysia, the team reproduced the breeding conditions in the Amazon during the dry season to encourage the fish to spawn. They lowered the water level and left it for a few hours before topping the tank up with cold water, and repeated the process until the pair was ready to lay their eggs. Buckley also collected samples of the orange mucus from the fish's flanks before they spawned and at various stages after the eggs had hatched, and monitored the parent's behaviour as their offspring grew.
During the first 3 days after hatching, the fry remained attached to the cone where the parents laid their eggs, absorbing the yolk and gaining strength until all of the fry were able to swim independently. Then they
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The Company of Biologists