A fish exhibiting mammalian behavior

From a report in the Journal of Experimental Biology:

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...

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 left the cone en masse and began feeding on their parents' mucus, feeding for up to 10 min by biting at the parent's side until the parent expertly ‘flicked’ the shoal over to its partner to continue feeding. The parents diligently fed their young intensely for 2 weeks...

Monitoring the composition of the parents' mucus before they spawned and through to the end of their parental responsibilities, Buckley found a huge increase in the mucus's antibody and protein levels when the parents laid their eggs, similar to the changes seen in mammalian milk around the time of birth. The protein and antibody levels remained high until the third week and returned to pre-spawning levels during the fourth week after hatching. Buckley suspects that the sudden increase in protein levels at spawning is hormonally regulated, much like the changes in mammalian milk...

Via Oregon Expat.